Digital broadcasting system and method of processing data

ABSTRACT

A digital broadcasting system and a data processing method are disclosed. Herein, additional encoding is performed on mobile service data, which are then transmitted, thereby providing robustness in the processed mobile service data, so that the mobile service data can respond more strongly against fast and frequent channel changes. The data processing method of a digital broadcast transmitting system includes the steps of forming a RS frame by grouping a plurality of mobile service data bytes that is being inputted, and performing error correction encoding in RS frame units, forming a super frame by grouping a plurality of the error correction encoded RS frame, performing row permutation in super frame units, and dividing the super frame back to RS frames, and dividing the RS frame into a plurality of data groups.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. application Ser. No.12/062,790 filed on Apr. 4, 2008 (now U.S. Pat. No. 8,074,147), whichclaims the benefit of and right of priority to the Korean PatentApplication No. 10-2007-0033907, filed on Apr. 5, 2007, and U.S.Provisional Application No. 60/911,509, filed on Apr. 12, 2007, thecontents of all of which are hereby incorporated by reference herein intheir entireties.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a digital broadcasting system andmethod of processing data.

2. Discussion of the Related Art

The Vestigial Sideband (VSB) transmission mode, which is adopted as thestandard for digital broadcasting in North America and the Republic ofKorea, is a system using a single carrier method. Therefore, thereceiving performance of the digital broadcast receiving system may bedeteriorated in a poor channel environment. Particularly, sinceresistance to changes in channels and noise is more highly required whenusing portable and/or mobile broadcast receivers, the receivingperformance may be even more deteriorated when transmitting mobileservice data by the VSB transmission mode.

SUMMARY OF THE INVENTION

Accordingly, the present invention is directed to a digital broadcastingsystem and a method of processing data that substantially obviate one ormore problems due to limitations and disadvantages of the related art.

An object of the present invention is to provide a digital broadcastingsystem and a method of processing data that are highly resistant tochannel changes and noise.

Another object of the present invention is to provide a digitalbroadcasting system and a method of processing data that can enhance thereceiving performance of a receiving system (or receiver) by having atransmitting system (or transmitter) perform additional encoding onmobile service data, and by having the receiving system (or receiver)perform decoding on the additionally encoded mobile service data as aninverse process of the transmitting system.

A further object of the present invention is to provide a digitalbroadcasting system and a method of processing data that can alsoenhance the receiving performance of a digital broadcast receivingsystem by inserting known data already known in accordance with a preagreement between the receiving system and the transmitting system in apredetermined area within a data area.

Additional advantages, objects, and features of the invention will beset forth in part in the description which follows and in part willbecome apparent to those having ordinary skill in the art uponexamination of the following or may be learned from practice of theinvention. The objectives and other advantages of the invention may berealized and attained by the structure particularly pointed out in thewritten description and claims hereof as well as the appended drawings.

To achieve these objects and other advantages and in accordance with thepurpose of the invention, as embodied and broadly described herein, adigital broadcast transmitting system includes a service multiplexer anda transmitter. The service multiplexer multiplexes mobile service dataand main service data at pre-determined data rates and, then, transmitsthe multiplexed service data to the transmitter. The transmitterperforms additional encoding on the mobile service data transmitted fromthe service multiplexer and, also, groups a plurality of mobile servicedata packets having encoding performed thereon so as to configure a datagroup.

Herein, the transmitter may multiplex a mobile service data packetincluding the mobile service data and a main service data packetincluding the main service data in packet units and may transmit themultiplexed data packets to a digital broadcast receiving system.Herein, the transmitter may multiplex the data group and the mainservice data packet in a burst structure, wherein the burst section maybe divided in a burst-on section including the data group, and aburst-off section that does not include the data group. The data groupmay be divided into a plurality of regions based upon a degree ofinterference of the main service data. A long known data sequence may beperiodically inserted in the region having no interference with the mainservice data.

In another aspect of the present invention, a digital broadcastreceiving system may use the known data sequence for demodulating andchannel equalizing processes. When receiving only the mobile servicedata, the digital broadcast receiving system turns power on only duringthe burst-on section so as to process the mobile service data.

In another aspect of the present invention, a data processing method ofa transmitting system includes the steps of forming a RS frame bygrouping a plurality of mobile service data bytes that is beinginputted, and performing error correction encoding in RS frame units,forming a super frame by grouping a plurality of the error correctionencoded RS frame, performing row permutation in super frame units, anddividing the super frame back to RS frames, and dividing the RS frameinto a plurality of data groups.

In another aspect of the present invention, a digital broadcasttransmitting system includes a first encoder, a second encoder, and agroup formatter. The first encoder forms a RS frame by grouping aplurality of mobile service data bytes that is being inputted andperforms error correction encoding in RS frame units. The first encoderthen forms a super frame by grouping a plurality of the error correctionencoded RS frame, performs row permutation in super frame units, anddivides the super frame back to RS frames. The second encoder performsencoding at a coding rate of 1/H on data within the RS frame, wherein His greater than or equal to 2 (i.e., H≧2). And, the group formatterdivides the encoded RS frame into a plurality of data groups andallocates each data group to each corresponding region.

In a further aspect of the present invention, in a data processingmethod of a digital broadcast receiving system, which receives a datagroup including error correction encoded mobile service data and errorcorrection decodes the received data group, the method includes thesteps of grouping a plurality of data groups, thereby forming an RSframe, generating a reliability map indicating reliability informationof each mobile service data byte within the RS frame, and performingerror correction on the RS frame by referring to the reliabilityinformation of the reliability map. Herein, the method further includesa step of performing error detection decoding on the RS frame, therebyindicating whether an error exists or not on an error flag correspondingto each row within the RS frame, and wherein the error correction isperformed on the RS frame by referring to a number of errors indicatedon the error flag and to the reliability information of the reliabilitymap.

It is to be understood that both the foregoing general description andthe following detailed description of the present invention areexemplary and explanatory and are intended to provide furtherexplanation of the invention as claimed.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings, which are included to provide a furtherunderstanding of the invention and are incorporated in and constitute apart of this application, illustrate embodiment(s) of the invention andtogether with the description serve to explain the principle of theinvention. In the drawings:

FIG. 1 illustrates a block diagram showing a general structure of adigital broadcasting system according to an embodiment of the presentinvention;

FIG. 2 illustrates a block diagram of a service multiplexer shown inFIG. 1 of the present invention;

FIG. 3 illustrates a block diagram of a transmitter shown in FIG. 1 ofthe present invention;

FIG. 4 illustrates a block diagram of a pre-processor shown in FIG. 3 ofthe present invention;

FIG. 5( a) to FIG. 5( e) illustrate process steps of error correctionencoding and error detection encoding according to an embodiment of thepresent invention;

FIG. 6( a) to FIG. 6( e) illustrate process steps of error correctionencoding and error detection encoding according to another embodiment ofthe present invention;

FIG. 7( a) to FIG. 7( d) illustrate process steps of error correctionencoding according to yet another embodiment of the present invention;

FIG. 8( a) to FIG. 8( d) illustrate process steps of row permutation insuper frame units according to an embodiment of the present invention;

FIG. 9( a) to FIG. 9( d) illustrate process steps of error correctionencoding according to yet another embodiment of the present invention;

FIG. 10( a) and FIG. 10( b) illustrate process steps of row permutationin super frame units according to another embodiment of the presentinvention;

FIG. 11( a) to FIG. 11( e) illustrate process steps of error correctionencoding according to yet another embodiment of the present invention;

FIG. 12( a) to FIG. 12( e) illustrate process steps of error correctionencoding according to yet another embodiment of the present invention;

FIG. 13( a) to FIG. 13( e) illustrate process steps of error correctionencoding according to yet another embodiment of the present invention;

FIG. 14A and FIG. 14B illustrate process steps of row permutation insuper frame units according to yet another embodiment of the presentinvention;

FIG. 15( a) and FIG. 15( b) illustrate an example of dividing the errorcorrection encoded RS frame into a plurality of sub-frames according tothe present invention;

FIG. 16( a) to FIG. 16( e) illustrate process steps of error correctionencoding according to yet another embodiment of the present invention;

FIG. 17A and FIG. 17B illustrate process steps of row permutation insuper frame units according to yet another embodiment of the presentinvention;

FIG. 18( a) and FIG. 18( b) illustrate another example of dividing theerror correction encoded RS frame into a plurality of sub-framesaccording to the present invention;

FIG. 19A and FIG. 19B respectively illustrate examples of datastructures before and after in a data deinterleaver of a digitalbroadcast transmitting system according to the present invention;

FIG. 20 illustrates an exemplary process of dividing an RS frame forconfiguring a data group according to the present invention;

FIG. 21( a) and FIG. 21( b) illustrate an exemplary process of dividingan RS frame for configuring a data group according to the presentinvention;

FIG. 22 illustrates exemplary operations of a packet multiplexer fortransmitting data groups according to an embodiment of the presentinvention;

FIG. 23 illustrates a block diagram showing a structure of a blockprocessor according to an embodiment of the present invention;

FIG. 24 illustrates a detailed block diagram of a symbol encoder shownin FIG. 23 of the present invention;

FIG. 25( a) to FIG. 25( c) illustrates a variable length interleavingprocess of a symbol interleaver shown in FIG. 23;

FIG. 26A and FIG. 26B illustrate a block diagram showing a structure ofa block processor according to another embodiment of the presentinvention;

FIG. 27( a) to FIG. 27( c) illustrate examples of block encoding andtrellis encoding according to an embodiment of the present invention;

FIG. 28 illustrates a block diagram of a trellis encoding moduleaccording to an embodiment of present invention;

FIG. 29A and FIG. 29B illustrate a concatenation between a blockprocessor and a trellis encoding module according to the presentinvention;

FIG. 30 illustrates a block diagram showing a structure of a blockprocessor according to another embodiment of the present invention;

FIG. 31 illustrates a block diagram showing a structure of a blockprocessor according to yet another embodiment of the present invention;

FIG. 32 illustrates an example wherein a group formatter inserts andtransmits a transmission parameter according to the present invention;

FIG. 33 illustrates an example wherein a block processor inserts andtransmits a transmission parameter according to the present invention;

FIG. 34 illustrates an example wherein a packet formatter inserts andtransmits a transmission parameter according to the present invention;

FIG. 35 illustrates an example wherein a transmission parameteraccording to the present invention is inserted in a fieldsynchronization segment region;

FIG. 36 illustrates a block diagram showing a structure of a digitalbroadcast receiving system according to the present invention;

FIG. 37 illustrates process steps of error correction decoding accordingto an embodiment of the present invention;

FIG. 38 illustrates process steps of error correction decoding accordingto another embodiment of the present invention;

FIG. 39 to FIG. 41 illustrate process steps of error correction decodingaccording to yet another embodiment of the present invention;

FIG. 42 illustrates process steps of error correction decoding accordingto yet another embodiment of the present invention;

FIG. 43 illustrates process steps of error correction decoding accordingto yet another embodiment of the present invention;

FIG. 44 illustrates detailed operations of an error correction decodingprocess by combining the first sub-frame and the second sub-frame shownin FIG. 43; and

FIG. 45 illustrates process steps of error correction decoding accordingto yet another embodiment of the present invention.

DETAILED DESCRIPTION OF THE INVENTION

Reference will now be made in detail to the preferred embodiments of thepresent invention, examples of which are illustrated in the accompanyingdrawings. Wherever possible, the same reference numbers will be usedthroughout the drawings to refer to the same or like parts. In addition,although the terms used in the present invention are selected fromgenerally known and used terms, some of the terms mentioned in thedescription of the present invention have been selected by the applicantat his or her discretion, the detailed meanings of which are describedin relevant parts of the description herein. Furthermore, it is requiredthat the present invention is understood, not simply by the actual termsused but by the meaning of each term lying within.

Among the terms used in the description of the present invention, mainservice data correspond to data that can be received by a fixedreceiving system and may include audio/video (A/V) data. Morespecifically, the main service data may include A/V data of highdefinition (HD) or standard definition (SD) levels and may also includediverse data types required for data broadcasting. Also, the known datacorrespond to data pre-known in accordance with a pre-arranged agreementbetween the receiving system and the transmitting system. Additionally,in the present invention, mobile service data may include at least oneof mobile service data, pedestrian service data, and handheld servicedata, and are collectively referred to as mobile service data forsimplicity. Herein, the mobile service data not only correspond tomobile/pedestrian/handheld service data (M/P/H service data) but mayalso include any type of service data with mobile or portablecharacteristics. Therefore, the mobile service data according to thepresent invention are not limited only to the M/P/H service data.

The above-described mobile service data may correspond to data havinginformation, such as program execution files, stock information, and soon, and may also correspond to A/V data. Most particularly, the mobileservice data may correspond to A/V data having lower resolution andlower data rate as compared to the main service data. For example, if anA/V codec that is used for a conventional main service corresponds to aMPEG-2 codec, a MPEG-4 advanced video coding (AVC) or scalable videocoding (SVC) having better image compression efficiency may be used asthe A/V codec for the mobile service. Furthermore, any type of data maybe transmitted as the mobile service data. For example, transportprotocol expert group (TPEG) data for broadcasting real-timetransportation information may be serviced as the main service data.

Also, a data service using the mobile service data may include weatherforecast services, traffic information services, stock informationservices, viewer participation quiz programs, real-time polls & surveys,interactive education broadcast programs, gaming services, servicesproviding information on synopsis, character, background music, andfilming sites of soap operas or series, services providing informationon past match scores and player profiles and achievements, and servicesproviding information on product information and programs classified byservice, medium, time, and theme enabling purchase orders to beprocessed. Herein, the present invention is not limited only to theservices mentioned above. In the present invention, the transmittingsystem provides backward compatibility in the main service data so as tobe received by the conventional receiving system. Herein, the mainservice data and the mobile service data are multiplexed to the samephysical channel and then transmitted.

The transmitting system according to the present invention performsadditional encoding on the mobile service data and inserts the dataalready known by the receiving system and transmitting system (i.e.,known data), thereby transmitting the processed data. Therefore, whenusing the transmitting system according to the present invention, thereceiving system may receive the mobile service data during a mobilestate and may also receive the mobile service data with stabilitydespite various distortion and noise occurring within the channel.

General Description of a Transmitting System

FIG. 1 illustrates a block diagram showing a general structure of adigital broadcast transmitting system according to an embodiment of thepresent invention. Herein, the digital broadcast transmitting includes aservice multiplexer 100 and a transmitter 200. Herein, the servicemultiplexer 100 is located in the studio of each broadcast station, andthe transmitter 200 is located in a site placed at a predetermineddistance from the studio. The transmitter 200 may be located in aplurality of different locations. Also, for example, the plurality oftransmitters may share the same frequency. And, in this case, theplurality of transmitters receives the same signal. Accordingly, in thereceiving system, a channel equalizer may compensate signal distortion,which is caused by a reflected wave, so as to recover the originalsignal. In another example, the plurality of transmitters may havedifferent frequencies with respect to the same channel.

A variety of methods may be used for data communication each of thetransmitters, which are located in remote positions, and the servicemultiplexer. For example, an interface standard such as a synchronousserial interface for transport of MPEG-2 data (SMPTE-310M). In theSMPTE-310M interface standard, a constant data rate is decided as anoutput data rate of the service multiplexer. For example, in case of the8VSB mode, the output data rate is 19.39 Mbps, and, in case of the 16VSBmode, the output data rate is 38.78 Mbps. Furthermore, in theconventional 8VSB mode transmitting system, a transport stream (TS)packet having a data rate of approximately 19.39 Mbps may be transmittedthrough a single physical channel. Also, in the transmitting systemaccording to the present invention provided with backward compatibilitywith the conventional transmitting system, additional encoding isperformed on the mobile service data. Thereafter, the additionallyencoded mobile service data are multiplexed with the main service datato a TS packet form, which is then transmitted. At this point, the datarate of the multiplexed TS packet is approximately 19.39 Mbps.

At this point, the service multiplexer 100 receives at least one type ofmobile service data and program specific information (PSI)/program andsystem information protocol (PSIP) table data for each mobile serviceand encapsulates the received data to each transport stream (TS) packet.Also, the service multiplexer 100 receives at least one type of mainservice data and PSI/PSIP table data for each main service so as toencapsulate the received data to a TS packet. Subsequently, the TSpackets are multiplexed according to a predetermined multiplexing ruleand outputs the multiplexed packets to the transmitter 200.

Service Multiplexer

FIG. 2 illustrates a block diagram showing an example of the servicemultiplexer. The service multiplexer includes a controller 110 forcontrolling the overall operations of the service multiplexer, aPSI/PSIP generator 120 for the main service, a PSI/PSIP generator 130for the mobile service, a null packet generator 140, a mobile servicemultiplexer 150, and a transport multiplexer 160. The transportmultiplexer 160 may include a main service multiplexer 161 and atransport stream (TS) packet multiplexer 162. Referring to FIG. 2, atleast one type of compression encoded main service data and the PSI/PSIPtable data generated from the PSI/PSIP generator 120 for the mainservice are inputted to the main service multiplexer 161 of thetransport multiplexer 160. The main service multiplexer 161 encapsulateseach of the inputted main service data and PSI/PSIP table data to MPEG-2TS packet forms. Then, the MPEG-2 TS packets are multiplexed andoutputted to the TS packet multiplexer 162. Herein, the data packetbeing outputted from the main service multiplexer 161 will be referredto as a main service data packet for simplicity.

Thereafter, at least one type of the compression encoded mobile servicedata and the PSI/PSIP table data generated from the PSI/PSIP generator130 for the mobile service are inputted to the mobile servicemultiplexer 150. The mobile service multiplexer 150 encapsulates each ofthe inputted mobile service data and PSI/PSIP table data to MPEG-TSpacket forms. Then, the MPEG-2 TS packets are multiplexed and outputtedto the TS packet multiplexer 162. Herein, the data packet beingoutputted from the mobile service multiplexer 150 will be referred to asa mobile service data packet for simplicity. At this point, thetransmitter 200 requires identification information in order to identifyand process the main service data packet and the mobile service datapacket. Herein, the identification information may use valuespre-decided in accordance with an agreement between the transmittingsystem and the receiving system, or may be configured of a separate setof data, or may modify predetermined location value with in thecorresponding data packet. As an example of the present invention, adifferent packet identifier (PID) may be assigned to identify each ofthe main service data packet and the mobile service data packet.

In another example, by modifying a synchronization data byte within aheader of the mobile service data, the service data packet may beidentified by using the synchronization data byte value of thecorresponding service data packet. For example, the synchronization byteof the main service data packet directly outputs the value decided bythe ISO/IEC13818-1 standard (i.e., 0x47) without any modification. Thesynchronization byte of the mobile service data packet modifies andoutputs the value, thereby identifying the main service data packet andthe mobile service data packet. Conversely, the synchronization byte ofthe main service data packet is modified and outputted, whereas thesynchronization byte of the mobile service data packet is directlyoutputted without being modified, thereby enabling the main service datapacket and the mobile service data packet to be identified.

A plurality of methods may be applied in the method of modifying thesynchronization byte. For example, each bit of the synchronization bytemay be inversed, or only a portion of the synchronization byte may beinversed. As described above, any type of identification information maybe used to identify the main service data packet and the mobile servicedata packet. Therefore, the scope of the present invention is notlimited only to the example set forth in the description of the presentinvention.

Meanwhile, a transport multiplexer used in the conventional digitalbroadcasting system may be used as the transport multiplexer 160according to the present invention. More specifically, in order tomultiplex the mobile service data and the main service data and totransmit the multiplexed data, the data rate of the main service islimited to a data rate of (19.39-K) Mbps. Then, K Mbps, whichcorresponds to the remaining data rate, is assigned as the data rate ofthe mobile service. Thus, the transport multiplexer which is alreadybeing used may be used as it is without any modification. Herein, thetransport multiplexer 160 multiplexes the main service data packet beingoutputted from the main service multiplexer 161 and the mobile servicedata packet being outputted from the mobile service multiplexer 150.Thereafter, the transport multiplexer 160 transmits the multiplexed datapackets to the transmitter 200.

However, in some cases, the output data rate of the mobile servicemultiplexer 150 may not be equal to K Mbps. In this case, the mobileservice multiplexer 150 multiplexes and outputs null data packetsgenerated from the null packet generator 140 so that the output datarate can reach K Mbps. More specifically, in order to match the outputdata rate of the mobile service multiplexer 150 to a constant data rate,the null packet generator 140 generates null data packets, which arethen outputted to the mobile service multiplexer 150. For example, whenthe service multiplexer 100 assigns K Mbps of the 19.39 Mbps to themobile service data, and when the remaining (19.39-K) Mbps is,therefore, assigned to the main service data, the data rate of themobile service data that are multiplexed by the service multiplexer 100actually becomes lower than K Mbps. This is because, in case of themobile service data, the pre-processor of the transmitting systemperforms additional encoding, thereby increasing the amount of data.Eventually, the data rate of the mobile service data, which may betransmitted from the service multiplexer 100, becomes smaller than KMbps.

For example, since the pre-processor of the transmitter performs anencoding process on the mobile service data at a coding rate of at least½, the amount of the data outputted from the pre-processor is increasedto more than twice the amount of the data initially inputted to thepre-processor. Therefore, the sum of the data rate of the main servicedata and the data rate of the mobile service data, both beingmultiplexed by the service multiplexer 100, becomes either equal to orsmaller than 19.39 Mbps. Therefore, in order to match the data rate ofthe data that are finally outputted from the service multiplexer 100 toa constant data rate (e.g., 19.39 Mbps), an amount of null data packetscorresponding to the amount of lacking data rate is generated from thenull packet generator 140 and outputted to the mobile servicemultiplexer 150.

Accordingly, the mobile service multiplexer 150 encapsulates each of themobile service data and the PSI/PSIP table data that are being inputtedto a MPEG-2 TS packet form. Then, the above-described TS packets aremultiplexed with the null data packets and, then, outputted to the TSpacket multiplexer 162. Thereafter, the TS packet multiplexer 162multiplexes the main service data packet being outputted from the mainservice multiplexer 161 and the mobile service data packet beingoutputted from the mobile service multiplexer 150 and transmits themultiplexed data packets to the transmitter 200 at a data rate of 19.39Mbps.

According to an embodiment of the present invention, the mobile servicemultiplexer 150 receives the null data packets. However, this is merelyexemplary and does not limit the scope of the present invention. Inother words, according to another embodiment of the present invention,the TS packet multiplexer 162 may receive the null data packets, so asto match the data rate of the finally outputted data to a constant datarate. Herein, the output path and multiplexing rule of the null datapacket is controlled by the controller 110. The controller 110 controlsthe multiplexing processed performed by the mobile service multiplexer150, the main service multiplexer 161 of the transport multiplexer 160,and the TS packet multiplexer 162, and also controls the null datapacket generation of the null packet generator 140. At this point, thetransmitter 200 discards the null data packets transmitted from theservice multiplexer 100 instead of transmitting the null data packets.

Further, in order to allow the transmitter 200 to discard the null datapackets transmitted from the service multiplexer 100 instead oftransmitting them, identification information for identifying the nulldata packet is required. Herein, the identification information may usevalues pre-decided in accordance with an agreement between thetransmitting system and the receiving system. For example, the value ofthe synchronization byte within the header of the null data packet maybe modified so as to be used as the identification information.Alternatively, a transport_error_indicator flag may also be used as theidentification information.

In the description of the present invention, an example of using thetransport_error_indicator flag as the identification information will begiven to describe an embodiment of the present invention. In this case,the transport_error_indicator flag of the null data packet is set to‘1’, and the transport_error_indicator flag of the remaining datapackets are reset to ‘0’, so as to identify the null data packet. Morespecifically, when the null packet generator 140 generates the null datapackets, if the transport_error_indicator flag from the header field ofthe null data packet is set to ‘1’ and then transmitted, the null datapacket may be identified and, therefore, be discarded. In the presentinvention, any type of identification information for identifying thenull data packets may be used. Therefore, the scope of the presentinvention is not limited only to the examples set forth in thedescription of the present invention.

According to another embodiment of the present invention, a transmissionparameter may be included in at least a portion of the null data packet,or at least one table or an operations and maintenance (OM) packet (orOMP) of the PSI/PSIP table for the mobile service. In this case, thetransmitter 200 extracts the transmission parameter and outputs theextracted transmission parameter to the corresponding block and alsotransmits the extracted parameter to the receiving system if required.More specifically, a packet referred to as an OMP is defined for thepurpose of operating and managing the transmitting system. For example,the OMP is configured in accordance with the MPEG-2 TS packet format,and the corresponding PID is given the value of 0x1FFA. The OMP isconfigured of a 4-byte header and a 184-byte payload. Herein, among the184 bytes, the first byte corresponds to an OM_type field, whichindicates the type of the OM packet.

In the present invention, the transmission parameter may be transmittedin the form of an OMP. And, in this case, among the values of thereserved fields within the OM_type field, a pre-arranged value is used,thereby indicating that the transmission parameter is being transmittedto the transmitter 200 in the form of an OMP. More specifically, thetransmitter 200 may find (or identify) the OMP by referring to the PID.Also, by parsing the OM_type field within the OMP, the transmitter 200can verify whether a transmission parameter is included after theOM_type field of the corresponding packet. The transmission parametercorresponds to supplemental data required for processing mobile servicedata from the transmitting system and the receiving system.

Herein, the transmission parameter may include data group information,region information within the data group, RS frame information, superframe information, burst information, turbo code information, and RScode information. The burst information may include burst sizeinformation, burst period information, and time information to nextburst. The burst period signifies the period at which the bursttransmitting the same mobile service is repeated. The data groupincludes a plurality of mobile service data packets, and a plurality ofsuch data groups is gathered (or grouped) to form a burst. A burstsection signifies the beginning of a current burst to the beginning of anext burst. Herein, the burst section is classified as a section thatincludes the data group (also referred to as a burst-on section), and asection that does not include the data group (also referred to as aburst-off section). A burst-on section is configured of a plurality offields, wherein one field includes one data group.

The transmission parameter may also include information on how signalsof a symbol domain are encoded in order to transmit the mobile servicedata, and multiplexing information on how the main service data and themobile service data or various types of mobile service data aremultiplexed. The information included in the transmission parameter ismerely exemplary to facilitate the understanding of the presentinvention. And, the adding and deleting of the information included inthe transmission parameter may be easily modified and changed by anyoneskilled in the art. Therefore, the present invention is not limited tothe examples proposed in the description set forth herein. Furthermore,the transmission parameters may be provided from the service multiplexer100 to the transmitter 200. Alternatively, the transmission parametersmay also be set up by an internal controller (not shown) within thetransmitter 200 or received from an external source.

Transmitter

FIG. 3 illustrates a block diagram showing an example of the transmitter200 according to an embodiment of the present invention. Herein, thetransmitter 200 includes a demultiplexer 210, a packet jitter mitigator220, a pre-processor 230, a packet multiplexer 240, a post-processor250, a synchronization (sync) multiplexer 260, and a transmission unit270. Herein, when a data packet is received from the service multiplexer100, the demultiplexer 210 should identify whether the received datapacket corresponds to a main service data packet, a mobile service datapacket, or a null data packet. For example, the demultiplexer 210 usesthe PID within the received data packet so as to identify the mainservice data packet and the mobile service data packet. Then, thedemultiplexer 210 uses a transport_error_indicator field to identify thenull data packet. The main service data packet identified by thedemultiplexer 210 is outputted to the packet jitter mitigator 220, themobile service data packet is outputted to the pre-processor 230, andthe null data packet is discarded. If a transmission parameter isincluded in the null data packet, then the transmission parameter isfirst extracted and outputted to the corresponding block. Thereafter,the null data packet is discarded.

The pre-processor 230 performs an additional encoding process of themobile service data included in the service data packet, which isdemultiplexed and outputted from the demultiplexer 210. Thepre-processor 230 also performs a process of configuring a data group sothat the data group may be positioned at a specific place in accordancewith the purpose of the data, which are to be transmitted on atransmission frame. This is to enable the mobile service data to respondswiftly and strongly against noise and channel changes. Thepre-processor 230 may also refer to the transmission parameter whenperforming the additional encoding process. Also, the pre-processor 230groups a plurality of mobile service data packets to configure a datagroup. Thereafter, known data, mobile service data, RS parity data, andMPEG header are allocated to pre-determined areas within the data group.

Pre-Processor within Transmitter

FIG. 4 illustrates a block diagram showing an example of thepre-processor 230 according to the present invention. The pre-processor230 includes a data randomizer 301, a RS frame encoder 302, a blockprocessor 303, a group formatter 304, a data deinterleaver 305, a packetformatter 306. The data randomizer 301 within the above-describedpre-processor 230 randomizes the mobile service data packet includingthe mobile service data that is inputted through the demultiplexer 210.Then, the data randomizer 301 outputs the randomized mobile service datapacket to the RS frame encoder 302. At this point, since the datarandomizer 301 performs the randomizing process on the mobile servicedata, the randomizing process that is to be performed by the datarandomizer 251 of the post-processor 250 on the mobile service data maybe omitted. The data randomizer 301 may also discard the synchronizationbyte within the mobile service data packet and perform the randomizingprocess. This is an option that may be chosen by the system designer. Inthe example given in the present invention, the randomizing process isperformed without discarding the synchronization byte within the mobileservice data packet.

The RS frame encoder 302 groups a plurality of mobile thesynchronization byte within the mobile service data packets that israndomized and inputted, so as to create a RS frame. Then, the RS frameencoder 302 performs at least one of an error correction encodingprocess and an error detection encoding process in RS frame units.Accordingly, robustness may be provided to the mobile service data,thereby scattering group error that may occur during changes in afrequency environment, thereby enabling the mobile service data torespond to the frequency environment, which is extremely vulnerable andliable to frequent changes. Also, the RS frame encoder 302 groups aplurality of RS frame so as to create a super frame, thereby performinga row permutation process in super frame units. The row permutationprocess may also be referred to as a row interleaving process.Hereinafter, the process will be referred to as row permutation forsimplicity.

More specifically, when the RS frame encoder 302 performs the process ofpermuting each row of the super frame in accordance with apre-determined rule, the position of the rows within the super framebefore and after the row permutation process is changed. If the rowpermutation process is performed by super frame units, and even thoughthe section having a plurality of errors occurring therein becomes verylong, and even though the number of errors included in the RS frame,which is to be decoded, exceeds the extent of being able to becorrected, the errors become dispersed within the entire super frame.Thus, the decoding ability is even more enhanced as compared to a singleRS frame.

At this point, as an example of the present invention, RS-encoding isapplied for the error correction encoding process, and a cyclicredundancy check (CRC) encoding is applied for the error detectionprocess. When performing the RS-encoding, parity data that are used forthe error correction are generated. And, when performing the CRCencoding, CRC data that are used for the error detection are generated.The RS encoding is one of forward error correction (FEC) methods. TheFEC corresponds to a technique for compensating errors that occur duringthe transmission process. The CRC data generated by CRC encoding may beused for indicating whether or not the mobile service data have beendamaged by the errors while being transmitted through the channel. Inthe present invention, a variety of error detection coding methods otherthan the CRC encoding method may be used, or the error correction codingmethod may be used to enhance the overall error correction ability ofthe receiving system. Herein, the RS frame encoder 302 refers to apre-determined transmission parameter and/or the transmission parameterprovided from the service multiplexer 100 so as to perform operationsincluding RS frame configuration, RS encoding, CRC encoding, super frameconfiguration, and row permutation in super frame units.

RS Frame Encoder within Pre-Processor

FIG. 5( a) to FIG. 5( e) illustrate error correction encoding and errordetection encoding processed according to an embodiment of the presentinvention. More specifically, the RS frame encoder 302 first divides theinputted mobile service data bytes to units of a predetermined length.The predetermined length is decided by the system designer. And, in theexample of the present invention, the predetermined length is equal to187 bytes, and, therefore, the 187-byte unit will be referred to as apacket for simplicity. For example, when the mobile service data thatare being inputted, as shown in FIG. 5( a), correspond to a MPEGtransport packet stream configured of 188-byte units, the firstsynchronization byte is removed, as shown in FIG. 5( b), so as toconfigure a 187-byte unit. Herein, the synchronization byte is removedbecause each mobile service data packet has the same value.

Herein, the process of removing the synchronization byte may beperformed during a randomizing process of the data randomizer 301 in anearlier process. In this case, the process of the removing thesynchronization byte by the RS frame encoder 302 may be omitted.Moreover, when adding synchronization bytes from the receiving system,the process may be performed by the data derandomizer instead of the RSframe decoder. Therefore, if a removable fixed byte (e.g.,synchronization byte) does not exist within the mobile service datapacket that is being inputted to the RS frame encoder 302, or if themobile service data that are being inputted are not configured in apacket format, the mobile service data that are being inputted aredivided into 187-byte units, thereby configuring a packet for each187-byte unit.

Subsequently, as shown in FIG. 5( c), N number of packets configured of187 bytes is grouped to configure a RS frame. At this point, the RSframe is configured as a RS frame having the size of N(row)*187(column)bytes, in which 187-byte packets are sequentially inputted in a rowdirection. In order to simplify the description of the presentinvention, the RS frame configured as described above will also bereferred to as a first RS frame. More specifically, only pure mobileservice data are included in the first RS frame, which is the same asthe structure configured of 187 N-byte rows. Thereafter, the mobileservice data within the RS frame are divided into an equal size. Then,when the divided mobile service data are transmitted in the same orderas the input order for configuring the RS frame, and when one or moreerrors have occurred at a particular point during thetransmitting/receiving process, the errors are clustered (or gathered)within the RS frame as well. In this case, the receiving system uses aRS erasure decoding method when performing error correction decoding,thereby enhancing the error correction ability. At this point, the Nnumber of columns within the N number of RS frame includes 187 bytes, asshown in FIG. 5( c).

In this case, a (Nc,Kc)-RS encoding process is performed on each column,so as to generate Nc-Kc (=P) number of parity bytes. Then, the newlygenerated P number of parity bytes is added after the very last byte ofthe corresponding column, thereby creating a column of (187+P) bytes.Herein, as shown in FIG. 5( c), Kc is equal to 187 (i.e., Kc=187), andNc is equal to 187+P (i.e., Nc=187+P). For example, when P is equal to48, (235,187)-RS encoding process is performed so as to create a columnof 235 bytes. When such RS encoding process is performed on all N numberof columns, as shown in FIG. 5( c), a RS frame having the size ofN(row)*(187+P)(column) bytes may be created, as shown in FIG. 5( d). Inorder to simplify the description of the present invention, the RS framehaving the RS parity inserted therein will be referred to as s second RSframe. More specifically, the second RS frame having the structure of(187+P) rows configured of N bytes may be configured.

As shown in FIG. 5( c) or FIG. 5( d), each row of the RS frame isconfigured of N bytes. However, depending upon channel conditionsbetween the transmitting system and the receiving system, error may beincluded in the RS frame. When errors occur as described above, CRC data(or CRC code or CRC checksum) may be used on each row unit in order toverify whether error exists in each row unit. The RS frame encoder 302may perform CRC encoding on the mobile service data being RS encoded soas to create (or generate) the CRC data. The CRC data being generated byCRC encoding may be used to indicate whether the mobile service datahave been damaged while being transmitted through the channel.

The present invention may also use different error detection encodingmethods other than the CRC encoding method. Alternatively, the presentinvention may use the error correction encoding method to enhance theoverall error correction ability of the receiving system. FIG. 5( e)illustrates an example of using a 2-byte (i.e., 16-bit) CRC checksum asthe CRC data. Herein, a 2-byte CRC checksum is generated for N number ofbytes of each row, thereby adding the 2-byte CRC checksum at the end ofthe N number of bytes. Thus, each row is expanded to (N+2) number ofbytes. Equation 1 below corresponds to an exemplary equation forgenerating a 2-byte CRC checksum for each row being configured of Nnumber of bytes.g(x)=x ¹⁶ +x ¹² +x ⁵+1  Equation 1

The process of adding a 2-byte checksum in each row is only exemplary.Therefore, the present invention is not limited only to the exampleproposed in the description set forth herein. In order to simplify theunderstanding of the present invention, the RS frame having the RSparity and CRC checksum added therein will hereinafter be referred to asa third RS frame. More specifically, the third RS frame corresponds to(187+P) number of rows each configured of (N+2) number of bytes. Asdescribed above, when the process of RS encoding and CRC encoding arecompleted, the (N*187)-byte RS frame is expanded to a (N+2)*(187+P)-byteRS frame. Furthermore, the RS frame that is expanded, as shown in FIG.5( e), is inputted to the block processor 303.

FIG. 6( a) to FIG. 6( e) illustrate examples showing the steps of anencoding process performed by the RS frame encoder 302 according toanother embodiment of the present invention. Herein, the RS frameencoding process of FIG. 6( a) to FIG. 6( e) is identical to the RSframe encoding process of FIG. 5( a) to FIG. 5( e) with the exception ofthe process step for forming the RS frame shown in FIG. 6( c). Morespecifically, when a 187-byte unit packet is formed through the processsteps of FIG. 6( a) and FIG. 6( b), a column is configured with the187-byte packet. Subsequently, N number of columns (i.e., N number ofpackets configuring each column) are sequentially grouped to form a RSframe having the size of N(rows)*187(columns), as shown in FIG. 6( c).In other words, an RS frame having the size of N*187 bytes is configuredby sequentially inserting N number of 187-byte packets in N number ofcolumns. Since the remaining process steps are identical to those shownin FIG. 5( d) and FIG. 5( e), a detailed description of the same will beomitted for simplicity.

FIG. 7( a) to FIG. 7( d) illustrate examples showing the steps of anencoding process performed by the RS frame encoder 302 according to yetanother embodiment of the present invention. In this example, theprocess step for error detection encoding is omitted. Referring to FIG.7, the process of forming a packet by grouping 187 mobile service databytes is identical to that described in FIG. 5 and FIG. 6. For example,if the mobile service data being inputted as shown in FIG. 7( a)correspond to a transport stream (TS) packet configured of 188-byteunits, the first synchronization byte is removed, as shown in FIG. 7(b), thereby configuring a packet with 187 bytes.

However, since the error detection encoding process is not performed inthe example shown in FIG. 7, N+2 number of packets configured of 187bytes is grouped to form a RS frame, as shown in FIG. 7( c). At thispoint, an RS frame may be configured by serially inserting in a rowdirection a 187-byte packet into a RS frame having the size of(N+2)(rows)*187(columns). Herein, each column of N number of RS framesincludes 187 bytes, as shown in FIG. 7( c). Therefore, in the presentinvention, a ((187+P),187)-RS encoding process is performed on eachcolumn, so as to generate P number of parity data bytes. Then, thegenerated P number of parity data bytes are added to the correspondingcolumn behind the last data byte of the column, thereby creating acolumn of (187+P) bytes. Also, when the ((187+P),187)-RS encodingprocess is performed, as shown in FIG. 7( d), on all N number ofcolumns, shown in FIG. 7( c), a RS frame having the size of(N+2)(rows)*(187+P)(columns) number of bytes may be created.

More specifically, the size of the RS frame being processed with errorcorrection encoding and error detection encoding, as shown in FIG. 5, isthe same as the size of the RS frame being process with error correctionencoding, as shown in FIG. 7. Herein, depending upon the type of theencoded mobile service data, the value P may either have the same valuesor have different values. For example, the value P of the first RS frameencoder 102 a may be set to be equal to 48 (i.e., P=48), and the value Pof the second RS frame encoder 102 b may be set to be equal to 36 (i.e.,P=36). If the value P is set to be equal to 48 is the first RS frameencoder 102 a, (235,187)-RS encoding is performed on each column,thereby creating 48 parity data bytes.

Based upon an error correction scenario of a RS frame, the data byteswithin the RS frame are transmitted through a channel in a rowdirection. At this point, when a large number of errors occur during alimited period of transmission time, errors also occur in a rowdirection within the RS frame being processed with a decoding process inthe receiving system. However, in the perspective of RS encodingperformed in a column direction, the errors are shown as beingscattered. Therefore, error correction may be performed moreeffectively. At this point, a method of increasing the number of paritydata bytes (P) may be used in order to perform a more intense errorcorrection process. However, using this method may lead to a decrease intransmission efficiency. Therefore, a mutually advantageous method isrequired. Furthermore, when performing the decoding process, an erasuredecoding process may be used to enhance the error correctionperformance.

The RS frame encoder according to the present invention also performs arow permutation (or interleaving) process in super frame units in orderto further enhance the error correction performance when errorcorrection the RS frame. FIG. 8 illustrates an example of performing arow permutation (or interleaving) process in super frame units accordingto the present invention. More specifically, G number of RS framesencoded as shown in FIG. 5 to FIG. 7 is grouped to form a super frame,as shown in FIG. 8( a). At this point, since each RS frame is formed of(N+2)*(187+P) number of bytes, one super frame is configured to have thesize of (N+2)*(187+P)*G bytes.

When a row permutation process permuting each row of the super frameconfigured as described above is performed based upon a pre-determinedpermutation rule, the positions of the rows prior to and after beingpermuted (or interleaved) within the super frame may be altered. Morespecifically, the i^(th) row of the super frame prior to theinterleaving process, as shown in FIG. 8( b), is positioned in thej^(th) row of the same super frame after the row permutation process.The above-described relation between i and j can be easily understoodwith reference to a permutation rule as shown in Equation 2 below.j=G(i mod(187+P))+└i/(187+P)┘i=(187+P)(j mod G)+└j/G┘  Equation 2

-   -   where 0≦i, j≦(187+P)G−1; or    -   where 0≦i, j<(187+P)G

Herein, each row of the super frame is configured of (N+2) number ofdata bytes even after being row-permuted in super frame units.

When all row permutation processes in super frame units are completed,the super frame is once again divided into G number of row-permuted RSframes, as shown in FIG. 8( d), and then provided to the block processor303. Herein, the number of RS parity bytes and the number of columnsshould be equally provided in each of the RS frames, which configure asuper frame. As described in the error correction scenario of a RSframe, in case of the super frame, a section having a large number oferror occurring therein is so long that, even when one RS frame that isto be decoded includes an excessive number of errors (i.e., to an extentthat the errors cannot be corrected), such errors are scatteredthroughout the entire super frame. Therefore, in comparison with asingle RS frame, the decoding performance of the super frame is moreenhanced. As described above, the mobile service data being encoded onRS frame units and row-permuted in super frame units by the RS frameencoders 302 are outputted to the block processor 303.

FIG. 9( a) to FIG. 9( d) illustrate examples showing the steps of anencoding process performed by the RS frame encoder 302 according to yetanother embodiment of the present invention. Referring to FIG. 9, theprocess of forming a packet by grouping 187 mobile service data bytes isidentical to that described in FIG. 5 to FIG. 7. Therefore, a detaileddescription of the same will be omitted for simplicity. Morespecifically, when a 187-byte unit packet is formed through the processsteps of FIG. 9( a) and FIG. 9( b), a plurality of packets is grouped toform a RS frame. In this embodiment of the present invention, a RS frameis formed by grouping 67 packets (i.e., rows), as shown in FIG. 9( c).

Subsequently, a (Nc,Kc)-RS encoding process is performed on each columnin the RS frame so as to generate Nc-Kc number of parity bytes. Then,the generated Nc-Kc number of parity bytes are added at the end portionof each corresponding column (i.e., after the 67^(th) row of eachcorresponding column). In this example, Nc is equal to 85, and Kc isequal to 67 (i.e., Nc=85 and Kc=67). Subsequently, the parity data beingadded to each column correspond to 18 bytes. Therefore, when the(85,67)-RS encoding process is performed on each of the 187 columnswithin the RS frame, an RS frame includes 187 bytes in each row and 85bytes in each column. In other words, the RS-encoded RS frame includes85 rows each configured of 187 bytes. In the present invention, thenumber of bytes configuring a packet, the number of rows configuring aRS frame, and Nc and Kc values used in RS encoding may vary dependingupon the design and condition of the system. Therefore, the presentinvention will not be limited only to the embodiments set forth herein.

Meanwhile, a CRC encoding process may be performed on the RS frameconfigured as shown in FIG. 9( d) according to the present invention.However, depending upon channel conditions between the transmittingsystem and the receiving system, error may be included in the RS frame.When errors occur as described above, CRC data (or CRC code or CRCchecksum) may be used on each row unit in order to verify whether errorexists in each row unit. The RS frame encoder 302 may perform CRCencoding on the mobile service data being RS encoded so as to create (orgenerate) the CRC data. The CRC data being generated by CRC encoding maybe used to indicate whether the mobile service data have been damagedwhile being transmitted through the channel. The present invention mayalso use different error detection encoding methods other than the CRCencoding method. Alternatively, the present invention may use the errorcorrection encoding method to enhance the overall error correctionability of the receiving system.

Either an 8-bit CRC checksum may be used as the CRC data, or a 16-bitCRC checksum may be used as the CRC data. For example, when using the8-bit CRC checksum, a 1-byte (i.e., 8-bit) CRC checksum is generated foreach row within the RS frame. Then, the generated 1-byte CRC checksum isadded to the respective row, thereby configuring the CRC data. At thispoint, the 1-byte CRC checksum may be added to any place (or position)within the corresponding row. According to the embodiment of the presentinvention, the CRC checksum may be added at the end portion of thecorresponding row, thereby configuring a 188-byte row. Furthermore, whenusing a 2-byte CRC checksum, a 2-byte (i.e., 16-bit) CRC checksum isgenerated for 2 rows. In this case, the generated 2-byte the 2-byte CRCchecksum may be added to any one of the 2 rows. Alternatively, a 1-byteCRC checksum may be added to each row. Also, when the RS frame iscreated by the RS encoding process, or when the RS frame is created bythe RS encoding and CRC encoding processes, a plurality of the RS framesis grouped to form a super frame. In this case, the row permutationprocess may be performed in super frame units.

When the RS frame is formed, as shown in FIG. 9, FIG. 10 illustrates theprocess steps for grouping a plurality of the RS frame to create a superframe and for performing row permutation in super frame units. When itis assumed that one row consists of 187 bytes and that (85,67)-RSencoding process is performed in FIG. 9, G number of RS frames eachconsisting of 85 rows are grouped to formed a super frame, whichconsists of a total of 85*G number of 187-byte rows, as shown in FIG.10( a). When the row permutation process is performed on theabove-described super frame by using a predetermined method, theposition of the rows may differ prior to and after the row permutationprocess within the super frame. More specifically, the i^(th) row of thesuper frame prior to the row permutation process of FIG. 10( a) ispositioned in the j^(th) row of the same super frame of FIG. 10( b),which is processed with row permutation. The above-described relationbetween i and j can be easily understood with reference to Equation 3below.j=G(i mod 85)+└i/85┘i=85(j mod G)└j/G┘  Equation 3

-   -   where 0≦i, j<85G

Herein, each row of the super frame is configured of 187 bytes evenafter being processed with row permutation in super frame units.Furthermore, once all super frame unit row permutation processes areperformed, the row-permuted super frame is divided back to G number ofRS frames, which are then provided to the block processor 303. At thispoint, the above-described CRC encoding process may either be performedeven before the super frame unit row permutation process, or beperformed after the row permutation process and the process of dividingthe row-permuted super frame to G number of RS frames. Alternatively, atleast any one or both of the CRC encoding process and the super frameunit row permutation process may be omitted.

Meanwhile, according to another embodiment of the present invention, aplurality of mobile service data packets may be grouped to form a RSframe, and a primary error correction encoding process may be performedin any one of a row direction or a column direction on the newly formedRS frame. Subsequently, a secondary error correction encoding processmay be performed in the other direction on the primarily errorcorrection encoded RS frame. In the description of the presentinvention, this process will be referred to as a double error correctionencoding process for simplicity.

FIG. 11( a) to FIG. 11( e) illustrate examples showing the steps of adouble error correction encoding process of the RS frame encoder 302according to an embodiment of the present invention. Referring to FIG.11, a primary error correction encoding process is performed in a rowdirection on the inputted mobile service data. And, subsequently, asecondary error correction encoding process is performed in a columndirection on the primarily error correction encoded mobile service data.For this, the RS frame encoder 302 should first configure a packet with187 bytes of mobile service data, as shown in FIG. 11( a) to FIG. 11(c). Thereafter, a plurality of such packets is grouped to form a singleRS frame. According to the embodiment of the present invention, 68packets (or rows) each consisting of 187 bytes are grouped to form a RSframe, as shown in FIG. 11( c).

A (Nr,Kr)-RS encoding process is performed on each of the 68 rows in theRS frame so as to generate Nr-Kr number of parity bytes. Then, thegenerated Nr-Kr number of parity bytes are added at the end portion ofeach corresponding row (i.e., after the 187^(th) column of eachcorresponding row). In this example, Nr is equal to 195, and Kr is equalto 187 (i.e., Nr=195 and Kr=187). Accordingly, the parity data beingadded to each row, as shown in FIG. 11( d), correspond to 8 bytes. Inother words, one row is being expanded from 187 bytes to 195 bytes. Asdescribed above, when the (195,187)-RS encoding process is performed oneach of the 68 rows within the RS frame, a RS frame including 195 bytesin each row and 68 bytes in each column is configured. Morespecifically, the primarily error correction encoded RS frame includes68 rows (or packets) each configured of 195 bytes.

Subsequently, a (Nc,Kc)-RS encoding process is performed on each columnin the RS frame, which is RS-encoded in the row direction as shown inFIG. 11( d), so as to generate Nc-Kc number of parity bytes. Then, thegenerated Nc-Kc number of parity bytes are added at the end portion ofeach corresponding column (i.e., after the 68^(th) row of eachcorresponding column). In this example, Nc is equal to 82, and Kc isequal to 68 (i.e., Nc=82 and Kc=68). Accordingly, the parity data beingadded to each column, as shown in FIG. 11( e), correspond to 14 bytes.In other words, one column is being expanded from 68 bytes to 82 bytes.As described above, when the (82,68)-RS encoding process is performed oneach of the 195 columns within the RS frame, a RS frame including 195bytes in each row and 82 bytes in each column is configured. In otherwords, the primarily and secondarily error correction encoded RS frameincludes 82 rows each configured of 195 bytes.

FIG. 12( a) to FIG. 12( e) illustrate examples showing the steps of adouble error correction encoding process of the RS frame encoder 302according to another embodiment of the present invention. Referring toFIG. 12, a primary error correction encoding process is performed in acolumn direction on the inputted mobile service data. And, subsequently,a secondary error correction encoding process is performed in a rowdirection on the primarily error correction encoded mobile service data.For this, the RS frame encoder 302 should first configure a packet with187 bytes of mobile service data, as shown in FIG. 12( a) to FIG. 12(c). Thereafter, a plurality of such packets is grouped to form a singleRS frame. According to the embodiment of the present invention, 68packets (or rows) each consisting of 187 bytes are grouped to form a RSframe, as shown in FIG. 12( c).

A (Nc,Kc)-RS encoding process is performed on each column in the RSframe so as to generate Nc-Kc number of parity bytes. Then, thegenerated Nc-Kc number of parity bytes are added at the end portion ofeach corresponding column (i.e., after the 68^(th) row of eachcorresponding column). In this example, Nc is equal to 82, and Kc isequal to 68 (i.e., Nc=82 and Kc=68). Accordingly, the parity data beingadded to each column, as shown in FIG. 12( d), correspond to 14 bytes.When the (82,68)-RS encoding process is performed on each of the 187columns within the RS frame, a RS frame including 187 bytes in each rowand 82 bytes in each column is configured. More specifically, theprimarily error correction encoded RS frame includes 82 rows eachconfigured of 187 bytes.

Subsequently, a (Nr,Kr)-RS encoding process is performed on each row inthe RS frame, which is RS-encoded in the column direction as shown inFIG. 12( d), so as to generate Nr-Kr number of parity bytes. Then, thegenerated Nr-Kr number of parity bytes are added at the end portion ofeach corresponding row (i.e., after the 187^(th) column of eachcorresponding row). In this example, Nr is equal to 195, and Kr is equalto 187 (i.e., Nr=195 and Kr=187). Accordingly, the parity data beingadded to each row, as shown in FIG. 12( e), correspond to 8 bytes. Whenthe (195,187)-RS encoding process is performed on each of the 82 rowswithin the RS frame, a RS frame including 195 bytes in each row and 82bytes in each column is configured. In other words, the primarily andsecondarily error correction encoded RS frame includes 82 rows eachconfigured of 195 bytes.

In the present invention, the number of bytes configuring a row, thenumber of rows configuring a RS frame, and Nr, Nc, Kr, and Kc valuesused in RS encoding during the double error correction encoding processmay vary depending upon the design and condition of the system.Therefore, the present invention will not be limited only to theembodiments set forth herein. Furthermore, a plurality of the doubleerror correction encoded RS frames, as shown in FIG. 11 or FIG. 12, maybe grouped to first configure a super frame. Thereafter, the rowpermutation process may be performed on newly formed super frame.Herein, by performing the row permutation process, group errors thatoccur during changes in a frequency environment may be scattered,thereby enabling the mobile service data to respond effectively to thefrequency environment, which is extremely vulnerable and liable tofrequent changes.

When the double error correction encoding process is performed in FIG.11 or FIG. 12, one RS frame is configured of 195(rows)*82(columns)bytes. Thereafter, G number of such RS frames is grouped to forms asuper frame configured of 82*G number of 195-byte rows. Subsequently,once the row permutation process is performed on the above-describedsuper frame, the positions of the rows prior to and after the rowpermutation process are changed. The row permutation process isidentical to that described in FIG. 8 or FIG. 10. Therefore, a detaileddescription of the same will be omitted for simplicity.

FIG. 13( a) to FIG. 13( e) illustrate examples showing the steps of adouble error correction encoding process of the RS frame encoder 302according to yet another embodiment of the present invention. Referringto FIG. 13, a primary error correction encoding process is performed ina column direction on the inputted mobile service data. And,subsequently, a secondary error correction encoding process is performedin a row direction on the primarily error correction encoded mobileservice data, thereby providing robustness to the mobile service data.In the embodiment shown in FIG. 13, the primary error correctionencoding process is performed in a row direction, and the secondaryerror correction encoding process is performed in a column direction.Furthermore, at least one of a super frame unit row permutation processand an error detection encoding process may be performed on thesecondarily error correction encoded mobile service data.

For this, the RS frame encoder 302 should first configure a packet with187 bytes of mobile service data, as shown in FIG. 13( a) to FIG. 13(c). Thereafter, a plurality of such packets is grouped to form a singleRS frame. According to the embodiment of the present invention, 67packets (or rows) each consisting of 187 bytes are grouped to form a RSframe, as shown in FIG. 13( c). A (Nc,Kc)-RS encoding process isperformed on each column in the RS frame so as to generate Nc-Kc numberof parity bytes. Then, the generated Nc-Kc number of parity bytes areadded at the end portion of each corresponding column (i.e., after the67^(th) row of each corresponding column). In this example, Nc is equalto 85, and Kc is equal to 67 (i.e., Nc=85 and Kc=67). Accordingly, theparity data being added to each column, as shown in FIG. 13( d),correspond to 18 bytes. When the (85,67)-RS encoding process isperformed on each of the 187 columns within the RS frame, a RS frameincluding 187 bytes in each row and 85 bytes in each column isconfigured. More specifically, the primarily error correction encoded RSframe includes 85 rows each configured of 187 bytes. In other words, allof the 187 columns of the RS frame include 85 bytes.

Subsequently, a (Nr,Kr)-RS encoding process is performed on each row inthe RS frame, which is RS-encoded in the column direction as shown inFIG. 13( d), so as to generate Nr-Kr number of parity bytes. Then, thegenerated Nr-Kr number of parity bytes are added at the end portion ofeach corresponding row (i.e., after the 187^(th) column of eachcorresponding row). In this example, Nr is equal to 201, and Kr is equalto 187 (i.e., Nr=201 and Kr=187). Accordingly, the parity data beingadded to each row, as shown in FIG. 13( e), correspond to 14 bytes. Whenthe (201,187)-RS encoding process is performed on each of the 85 rowswithin the RS frame, a RS frame including 201 bytes in each row and 85bytes in each column is configured. In other words, the RS frame that isobtained after the secondary error correction encoding process includes85 rows each configured of 201 bytes.

In the present invention, the number of bytes configuring a row, thenumber of rows configuring a RS frame, and Nr, Nc, Kr, and Kc valuesused in RS encoding during the double error correction encoding processmay vary depending upon the design and condition of the system.Therefore, the present invention will not be limited only to theembodiments set forth herein. Furthermore, the row permutation processmay be performed in super frame units on the primarily and secondarilyerror correction encoded mobile service data, as described above. Byperforming the row permutation process, group errors that occur duringchanges in a frequency environment may be scattered, thereby enablingthe mobile service data to respond effectively to the frequencyenvironment, which is extremely vulnerable and liable to frequentchanges.

For this, in the present invention, the secondarily error correctionencoded RS frame (i.e., the RS frame having 85 rows each configured of201 bytes) is first divided into 2 RS sub-frames. For example, themobile service data that are inputted to the RS frame encoder 302 forthe RS encoding process (i.e., payload data) and the parity data thatare generated by an RS encoding process performed in a column directionare collectively referred to as a “first RS sub-frame”. The parity datathat are generated by an RS encoding process performed in a rowdirection are referred to as a “second RS sub-frame”. Accordingly, thefirst RS sub-frame includes 85 units of 187 bytes, and the second RSsub-frame includes 85 units of 14 bytes. Then, a plurality of thedivided first RS sub-frames is grouped to form a first super frame, anda plurality of the divided second RS sub-frames is grouped to form asecond super frame. Thereafter, row permutation is performed on eachsuper frame.

FIG. 14A illustrates a row permutation process performed on the firstsuper frame, and FIG. 14B illustrates a row permutation processperformed on the second super frame. Referring to FIG. 14A, when a firstsuper frame including 187 bytes in each row and 85 bytes in each columnis configured, G number of first RS sub-frames are grouped to configurea first super frame consisting of 85*G number of 187-byte rows. When therow permutation process is performed on the above-described first superframe by using a predetermined method, the position of the rows maydiffer prior to and after the row permutation process within the firstsuper frame, as shown in FIG. 14A. More specifically, the i^(th) row ofthe first super frame prior to the row permutation process is positionedin the j^(th) row of the same first RS super frame after rowpermutation. The above-described relation between and j can be easilyunderstood with reference to Equation 4 below.j=G(i mod 85)+└i/85┘i=85(j mod G)+└j/G┘  Equation 4

-   -   where 0 j<85G

Herein, each row of the first super frame is configured of 187 byteseven after being processes with row permutation. Once the first superframe unit row permutation process is performed, the first super frameis divided back to G number of row-permuted first RS sub-frames, whichare then provided to the block processor 303.

Meanwhile, referring to FIG. 14B, when a second RS sub-frame including14 bytes in each row and 85 bytes in each column is configured, G numberof second RS sub-frames are grouped to configure a second super frameconsisting of 85*G number of 14-byte rows. When the row permutationprocess is performed on the above-described second super frame by usinga predetermined method, the position of the rows may differ prior to andafter the row permutation process within the second super frame, asshown in FIG. 14B. More specifically, the i^(th) row of the second superframe prior to the row permutation process is positioned in the j^(th)row of the same second super frame after row permutation. Similarly,each row of the second super frame is configured of 14 bytes even afterthe row permutation process is performed. The above-described relationbetween i and j of the second super frame may be applied to theabove-described Equation 4, or another row permutation method may beapplied herein.

In other words, Equation 4 corresponds to a row permutation methodaccording to an embodiment of the present invention. Any row permutationmethod in which i and j may include all rows within the super frames maybe used. The row permutation method is not limited only to the examplesgiven in the description of the present invention. Furthermore, in usingthe equation for performing row permutation on the first and secondsuper frames, the same equation may be used on both super frames, or adifferent equation may be used on each super frame. Furthermore, anerror detection encoding process may be performed on at least any one ofthe first and second super frames that is processed with rowpermutation. For example, CRC encoding may be used in the errordetection encoding process. Alternatively, any error detection encodingmethod other than the CRC encoding method may also be used. Furthermore,an error correction encoding method may be used to enhance the overallerror correction performance of the receiving system.

For example, when it is assumed that CRC encoding is applied to thefirst RS sub-frame and that the 1-byte (i.e., 8-bit) checksum is used asthe CRC data, the RS frame encoder 302 may generate a 1-byte (i.e.,8-bit) CRC checksum for each 187-byte row within the first RS sub-frame.Then, the generated 1-byte CRC checksum is added to the respective row.At this point, the 1-byte CRC checksum may be added to any place (orposition) within the corresponding row. According to the embodiment ofthe present invention, the CRC checksum may be added at the end portionof the corresponding row, thereby configuring a 188-byte row. In anotherexample, when it is assumed that CRC encoding is applied to the first RSsub-frame and that a 2-byte (i.e., 16-bit) CRC checksum is used, a2-byte (i.e., 16-bit) CRC checksum is generated for 2 rows. In thiscase, the generated 2-byte the 2-byte CRC checksum may be added to anyone of the 2 rows. At this point, the 2-byte CRC checksum may be addedto any place (or position) within the 2 rows. After adding the 2-byteCRC checksum to the predetermined position within the 2 rows, theprocessed data may be divided so as to configure 2 188-byte rows.Alternatively, a 2-byte (i.e., 16-bit) CRC checksum is generated for 2rows. Then, a 1-byte CRC checksum is added to the end of each row,thereby configuring 2 188-byte rows.

The CRC encoding process may be performed before the row permutationprocess, or the CRC encoding process may be performed after the rowpermutation process. For example, when the CRC encoding process isperformed after the row permutation process, the first super framehaving 85*G number of 187-byte rows is extended to a first super framehaving 85*G number of 188-byte rows. The CRC-encoded first super frameis then divided back to G number of first RS sub-frames. Therow-permuted second super frame is also divided back to G number ofsecond RS sub-frames. Thereafter, the divided first RS sub-frames andthe divided second RS sub-frames are inputted to the block processor303.

FIG. 15( a) illustrates a structure of a first RS sub-frame beingsequentially processed with RS-encoding, row permutation, andCRC-encoding and then being inputted to the block processor 303. Herein,the first RS sub-frame consists of 85 188-byte rows. FIG. 15( b)illustrates a structure of a second RS sub-frame being sequentiallyprocessed with RS-encoding and row permutation and then being inputtedto the block processor 303. Herein, the second RS sub-frame consists of85 14-byte rows.

FIG. 16( a) to FIG. 16( e) illustrate examples showing the steps of anerror correction encoding process of the RS frame encoder 302 accordingto another embodiment of the present invention. Referring to FIG. 16,inputted mobile service data packets are grouped to form a RS frame.Then, an error correction encoding process is performed in a columndirection on the RS frame. Also, the RS frame that is error correctionencoded in a column direction is divided into a first RS sub-frame and asecond RS sub-frame. Then, each of the first and second RS sub-framesmay be processed with at least one of a row permutation process and anerror detection encoding process. In order to do so, the RS frameencoder 302 should first configure a packet with 187 bytes of mobileservice data, as shown in FIG. 16( a) to FIG. 16( c). Thereafter, aplurality of such packets is grouped to form a single RS frame.According to the embodiment of the present invention, 67 packets (orrows) each consisting of 187 bytes are grouped to form a RS frame, asshown in FIG. 16( c).

A (Nc,Kc)-RS encoding process is performed on each column in the RSframe so as to generate Nc-Kc number of parity bytes. Then, thegenerated Nc-Kc number of parity bytes are added at the end portion ofeach corresponding column (i.e., after the 67^(th) row of eachcorresponding column). In this example, Nc is equal to 91, and Kc isequal to 67 (i.e., Nc=91 and Kc=67). Accordingly, the parity data beingadded to each column, as shown in FIG. 16( d), correspond to 24 bytes.When the (91,67)-RS encoding process is performed on each of the 187columns within the RS frame, a RS frame including 187 bytes in each rowand 91 bytes in each column is configured. More specifically, the errorcorrection encoded RS frame includes 91 rows each configured of 187bytes. In other words, each of the 187 columns included in the RS frameincludes 91 bytes.

In the present invention, the number of bytes configuring a row, thenumber of rows configuring a RS frame, and Nc and Kc values used in RSencoding during the double error correction encoding process may varydepending upon the design and condition of the system. Therefore, thepresent invention will not be limited only to the embodiments set forthherein. Furthermore, the row permutation process may be performed insuper frame units on the mobile service data error correction encoded ina column direction, as shown in FIG. 16( d). By performing the rowpermutation process, group errors that occur during changes in afrequency environment may be scattered, thereby enabling the mobileservice data to respond effectively to the frequency environment, whichis extremely vulnerable and liable to frequent changes.

For this, in the present invention, the error correction encoded RSframe (i.e., the RS frame having 91 rows each configured of 187 bytes)is divided into 2 RS sub-frames. For example, the rows of the mobileservice data that are inputted for the RS encoding process (i.e.,payload data) and part of the parity data rows (e.g., rows including 18parity data bytes among a total of 24 parity data byte generated by theRS encoding process performed in a column direction) are collectivelyreferred to as a “first RS sub-frame”. The rows including the remaining6 parity data byte are referred to as a “second RS sub-frame”.Accordingly, the first RS sub-frame includes 85 units of 187 bytes, asshown in FIG. 16( e), and the second RS sub-frame includes 6 units of187 bytes. Then, a plurality of the divided first RS sub-frames isgrouped to form a first super frame, and a plurality of the dividedsecond RS sub-frames is grouped to form a second super frame.Thereafter, row permutation is performed on each super frame.

FIG. 17A illustrates a row permutation process performed on the firstsuper frame, and FIG. 17B illustrates a row permutation processperformed on the second super frame. Referring to FIG. 17A, when a firstsuper frame including 187 bytes in each row and 85 bytes in each columnis configured, G number of first RS sub-frames are grouped to configurea first super frame consisting of 85*G number of 187-byte rows. At thispoint, the structure of the first super frame shown in FIG. 17A isidentical to the structure of the first super frame shown in FIG. 14A.Therefore, since the row permutation process of the first super frameshown in FIG. 17A is also identical to that of the first super frameshown in FIG. 14A, a detailed description of the same will be omittedfor simplicity.

Meanwhile, referring to FIG. 17B, the row permutation process of thesecond RS sub-frame will be described in detail. More specifically, whena second RS sub-frame including 187 bytes in each row and 6 bytes ineach column is configured, G number of second RS sub-frames are groupedto configure a second super frame consisting of 6*G number of 187-byterows. When the row permutation process is performed on theabove-described second super frame by using a predetermined method, theposition of the rows may differ prior to and after the row permutationprocess within the second super frame, as shown in FIG. 17B. Morespecifically, the i^(th) row of the second super frame prior to the rowpermutation process is positioned in the j^(th) row of the same secondsuper frame after row permutation. Similarly, each row of the secondsuper frame is configured of 187 bytes even after the row permutationprocess is performed. The above-described relation between i and j canbe easily understood with reference to Equation 5 below.j=G(i mod 6)+└i/6┘i=6(j mod G)+└j/G┘  Equation 5

-   -   where 0≦i, j<6G

More specifically, Equation 5 corresponds to a row permutation methodaccording to another embodiment of the present invention. Any rowpermutation method in which i and j may include all rows within thesuper frame may be used. The row permutation method is not limited onlyto the examples given in the description of the present invention. Alsoin the other embodiment of the present invention, in using the equationfor performing row permutation on the first and second super frames, thesame equation may be used on both super frames, or a different equationmay be used on each super frame. For example, CRC encoding may be usedin the error detection encoding process. Alternatively, any errordetection encoding method other than the CRC encoding method may also beused. Furthermore, an error correction encoding method may be used toenhance the overall error correction performance of the receivingsystem.

When it is assumed that CRC encoding is applied to the first and secondRS sub-frames and that the 1-byte (i.e., 8-bit) checksum is used as theCRC data, the RS frame encoder 302 may generate a 1-byte (i.e., 8-bit)CRC checksum for each 187-byte row within the first and second RSsub-frames. Then, the generated 1-byte CRC checksum is added to therespective row. At this point, the 1-byte CRC checksum may be added toany place (or position) within the corresponding row. According to theembodiment of the present invention, the CRC checksum may be added atthe end portion of the corresponding row, thereby configuring a 188-byterow.

In another example, when it is assumed that CRC encoding is applied tothe first and second RS sub-frames and that a 2-byte (i.e., 16-bit) CRCchecksum is used, a 2-byte (i.e., 16-bit) CRC checksum is generated for2 rows. In this case, the generated 2-byte the 2-byte CRC checksum maybe added to any one of the 2 rows. At this point, the 2-byte CRCchecksum may be added to any place (or position) within the 2 rows.After adding the 2-byte CRC checksum to the predetermined positionwithin the 2 rows, the processed data may be divided so as to configure2 188-byte rows. Alternatively, a 2-byte (i.e., 16-bit) CRC checksum isgenerated for 2 rows. Then, a 1-byte CRC checksum is added to the end ofeach row, thereby configuring 2 188-byte rows.

The CRC encoding process may be performed before the row permutationprocess, or the CRC encoding process may be performed after the rowpermutation process. For example, when the CRC encoding process isperformed after the row permutation process, the first super framehaving 85*G number of 187-byte rows is extended to a first super framehaving 85*G number of 188-byte rows. Also, the second super frame having6*G number of 187-byte rows is extended to a second super frame having6*G number of 188-byte rows. The CRC-encoded first and second superframes are, then, each divided back to G number of first and second RSsub-frames. Thereafter, the divided first RS sub-frames and the dividedsecond RS sub-frames are inputted to the block processor 303.

FIG. 18( a) illustrates a structure of a first RS sub-frame beingsequentially processed with RS-encoding, row permutation, andCRC-encoding and then being inputted to the block processor 303. Herein,the first RS sub-frame consists of 85 188-byte rows. FIG. 18( b)illustrates a structure of a second RS sub-frame being sequentiallyprocessed with RS-encoding and row permutation and then being inputtedto the block processor 303. Herein, the second RS sub-frame consists of6 188-byte rows.

The coding rates for the above-described column direction RS encodingprocess and row direction RS encoding process may be used in anycombination that best fits the system structure. Additionally, thecorresponding coding rates may be used not only for the RS encodingprocesses but also for other error correction encoding processes.Furthermore, when performing row permutation in super frame units, thesize of the RS sub-frames after the row permutation process is notnecessarily required to be identical to the size of the RS sub-framesprior to the row permutation process. Nevertheless, the total number ofrows included in the super frame should remain the same. Morespecifically, if G number of RS sub-frames are included in a super frameprior to row permutation, and if N number of rows are included in asingle RS sub-frame, the number of RS sub-frames included in a superframe after row permutation becomes equal to G/2 (wherein G is an evennumber), and the number of row included in a single RS sub-frame becomesequal to 2N. Since there is no actual change in the total number of rowsincluded in a super frame, the row permutation operation may beperformed without difficulty. Therefore, the system designer mayrandomly decide the size of each RS sub-frame prior to and after rowpermutation.

As described above, the mobile service data encoded by the RS frameencoder 302 are inputted to the block processor 303. The block processor303 then encodes the inputted mobile service data at a coding rate ofG/H (wherein, G is smaller than H (i.e., G<H)) and then outputted to thegroup formatter 304. More specifically, the block processor 303 dividesthe mobile service data being inputted in byte units into bit units.Then, the G number of bits is encoded to H number of bits. Thereafter,the encoded bits are converted back to byte units and then outputted.For example, if 1 bit of the input data is coded to 2 bits andoutputted, then G is equal to 1 and H is equal to 2 (i.e., G=1 and H=2).Alternatively, if 1 bit of the input data is coded to 4 bits andoutputted, then G is equal to 1 and H is equal to 4 (i.e., G=1 and H=4).Hereinafter, the former coding rate will be referred to as a coding rateof ½ (½-rate coding), and the latter coding rate will be referred to asa coding rate of ¼ (¼-rate coding), for simplicity.

Herein, when using the ¼ coding rate, the coding efficiency is greaterthan when using the ½ coding rate, and may, therefore, provide greaterand enhanced error correction ability. For such reason, when it isassumed that the data encoded at a ¼ coding rate in the group formatter304, which is located near the end portion of the system, are allocatedto an area in which the receiving performance may be deteriorated, andthat the data encoded at a ½ coding rate are allocated to an area havingexcellent receiving performance, the difference in performance may bereduced. At this point, the block processor 303 may also receivesignaling information including transmission parameters. Herein, thesignaling information may also be processed with either ½-rate coding or¼-rate coding as in the step of processing mobile service data.Thereafter, the signaling information is also considered the same as themobile service data and processed accordingly.

Meanwhile, the group formatter inserts mobile service data that areoutputted from the block processor 303 in corresponding areas within adata group, which is configured in accordance with a pre-defined rule.Also, with respect to the data deinterleaving process, each place holderor known data (or known data place holders) are also inserted incorresponding areas within the data group. At this point, the data groupmay be divided into at least one hierarchical area. Herein, the type ofmobile service data being inserted in each area may vary depending uponthe characteristics of each hierarchical area. Additionally, each areamay, for example, be divided based upon the receiving performance withinthe data group. Furthermore, one data group may be configured to includea set of field synchronization data.

In an example given in the present invention, a data group is dividedinto A, B, and C regions in a data configuration prior to datadeinterleaving. At this point, the group formatter 304 allocates themobile service data, which are inputted after being RS encoded and blockencoded, to each of the corresponding regions by referring to thetransmission parameter. FIG. 19A illustrates an alignment of data afterbeing data interleaved and identified, and FIG. 19B illustrates analignment of data before being data interleaved and identified. Morespecifically, a data structure identical to that shown in FIG. 19A istransmitted to a receiving system. Also, the data group configured tohave the same structure as the data structure shown in FIG. 19A isinputted to the data deinterleaver 305.

As described above, FIG. 19A illustrates a data structure prior to datadeinterleaving that is divided into 3 regions, such as region A, regionB, and region C. Also, in the present invention, each of the regions Ato C is further divided into a plurality of regions. Referring to FIG.19A, region A is divided into 5 regions (A1 to A5), region B is dividedinto 2 regions (B1 and B2), and region C is divided into 3 regions (C1to C3). Herein, regions A to C are identified as regions having similarreceiving performances within the data group. Herein, the type of mobileservice data, which are inputted, may also vary depending upon thecharacteristic of each region.

In the example of the present invention, the data structure is dividedinto regions A to C based upon the level of interference of the mainservice data. Herein, the data group is divided into a plurality ofregions to be used for different purposes. More specifically, a regionof the main service data having no interference or a very lowinterference level may be considered to have a more resistant (orstronger) receiving performance as compared to regions having higherinterference levels. Additionally, when using a system inserting andtransmitting known data in the data group, and when consecutively longknown data are to be periodically inserted in the mobile service data,the known data having a predetermined length may be periodicallyinserted in the region having no interference from the main service data(e.g., region A). However, due to interference from the main servicedata, it is difficult to periodically insert known data and also toinsert consecutively long known data to a region having interferencefrom the main service data (e.g., region B and region C).

Hereinafter, examples of allocating data to region A (A1 to A5), regionB (B1 and B2), and region C (C1 to C3) will now be described in detailwith reference to FIG. 19A. The data group size, the number ofhierarchically divided regions within the data group and the size ofeach region, and the number of mobile service data bytes that can beinserted in each hierarchically divided region of FIG. 19A are merelyexamples given to facilitate the understanding of the present invention.Herein, the group formatter 304 creates a data group including places inwhich field synchronization data bytes are to be inserted, so as tocreate the data group that will hereinafter be described in detail.

More specifically, region A is a region within the data group in which along known data sequence may be periodically inserted, and in whichincludes regions wherein the main service data are not mixed (e.g., A2to A5). Also, region A includes a region (e.g., A1) located between afield synchronization region and the region in which the first knowndata sequence is to be inserted. The field synchronization region hasthe length of one segment (i.e., 832 symbols) existing in an ATSCsystem.

For example, referring to FIG. 19A, 2428 bytes of the mobile servicedata may be inserted in region A1, 2580 bytes may be inserted in regionA2, 2772 bytes may be inserted in region A3, 2472 bytes may be insertedin region A4, and 2772 bytes may be inserted in region A5. Herein,trellis initialization data or known data, MPEG header, and RS parityare not included in the mobile service data. As described above, whenregion A includes a known data sequence at both ends, the receivingsystem uses channel information that can obtain known data or fieldsynchronization data, so as to perform equalization, thereby providingenforced equalization performance.

Also, region B includes a region located within 8 segments at thebeginning of a field synchronization region within the data group(chronologically placed before region A1) (e.g., region B1), and aregion located within 8 segments behind the very last known datasequence which is inserted in the data group (e.g., region B2). Forexample, 930 bytes of the mobile service data may be inserted in theregion B1, and 1350 bytes may be inserted in region B2. Similarly,trellis initialization data or known data, MPEG header, and RS parityare not included in the mobile service data. In case of region B, thereceiving system may perform equalization by using channel informationobtained from the field synchronization region. Alternatively, thereceiving system may also perform equalization by using channelinformation that may be obtained from the last known data sequence,thereby enabling the system to respond to the channel changes.

Region C includes a region located within 30 segments including andpreceding the 9^(th) segment of the field synchronization region(chronologically located before region A) (e.g., region C1), a regionlocated within 12 segments including and following the 9^(th) segment ofthe very last known data sequence within the data group (chronologicallylocated after region A) (e.g., region C2), and a region located in 32segments after the region C2 (e.g., region C3). For example, 1272 bytesof the mobile service data may be inserted in the region C1, 1560 bytesmay be inserted in region C2, and 1312 bytes may be inserted in regionC3. Similarly, trellis initialization data or known data, MPEG header,and RS parity are not included in the mobile service data. Herein,region C (e.g., region C1) is located chronologically earlier than (orbefore) region A.

Since region C (e.g., region C1) is located further apart from the fieldsynchronization region which corresponds to the closest known dataregion, the receiving system may use the channel information obtainedfrom the field synchronization data when performing channelequalization. Alternatively, the receiving system may also use the mostrecent channel information of a previous data group. Furthermore, inregion C (e.g., region C2 and region C3) located before region A, thereceiving system may use the channel information obtained from the lastknown data sequence to perform equalization. However, when the channelsare subject to fast and frequent changes, the equalization may not beperformed perfectly. Therefore, the equalization performance of region Cmay be deteriorated as compared to that of region B.

When it is assumed that the data group is allocated with a plurality ofhierarchically divided regions, as described above, the block processor303 may encode the mobile service data, which are to be inserted to eachregion based upon the characteristic of each hierarchical region, at adifferent coding rate. For example, the block processor 303 may encodethe mobile service data, which are to be inserted in regions A1 to A5 ofregion A, at a coding rate of ½. Then, the group formatter 304 mayinsert the ½-rate encoded mobile service data to regions A1 to A5.

The block processor 303 may encode the mobile service data, which are tobe inserted in regions B1 and B2 of region B, at a coding rate of ¼having higher error correction ability as compared to the ½-coding rate.Then, the group formatter 304 inserts the ¼-rate coded mobile servicedata in region B1 and region B2. Furthermore, the block processor 303may encode the mobile service data, which are to be inserted in regionsC1 to C3 of region C, at a coding rate of ¼ or a coding rate havinghigher error correction ability than the ¼-coding rate. Then, the groupformatter 304 may either insert the encoded mobile service data toregions C1 to C3, as described above, or leave the data in a reservedregion for future usage.

For example, when the RS frame encoder 302 performs double errorcorrection encoding, error detection encoding, and row permutation ofsuper frame unit as shown in FIG. 13, FIG. 14( a), and FIG. 14( b), andconfigures the first RS sub_frame and the second RS sub_frame as shownin FIG. 15( a) and FIG. 15( b), the first RS sub_frame via the blockprocessor 303 may assign regions A and B within the data group, thesecond RS sub_frame via the block processor 303 may assign region cwithin the data group by the group formatter 304.

In another example, when the RS frame encoder 302 performs double errorcorrection encoding, error detection encoding, and row permutation ofsuper frame unit as shown in FIG. 16, FIG. 17( a), and FIG. 17( b), andconfigures the first RS sub_frame and the second RS sub_frame as shownin FIG. 18( a) and FIG. 18( b), the first RS sub_frame via the blockprocessor 303 may assign regions A and B within the data group, thesecond RS sub_frame via the block processor 303 may assign region cwithin the data group by the group formatter 304.

In addition, the group formatter 304 also inserts supplemental data,such as signaling information that notifies the overall transmissioninformation, other than the mobile service data in the data group. Also,apart from the encoded mobile service data outputted from the blockprocessor 303, the group formatter 304 also inserts MPEG header placeholders, non-systematic RS parity place holders, main service data placeholders, which are related to data deinterleaving in a later process, asshown in FIG. 19A. Herein, the main service data place holders areinserted because the mobile service data bytes and the main service databytes are alternately mixed with one another in regions B and C basedupon the input of the data deinterleaver, as shown in FIG. 19A. Forexample, based upon the data outputted after data deinterleaving, theplace holder for the MPEG header may be allocated at the very beginningof each packet.

Furthermore, the group formatter 304 either inserts known data generatedin accordance with a pre-determined method or inserts known data placeholders for inserting the known data in a later process. Additionally,place holders for initializing the trellis encoding module 256 are alsoinserted in the corresponding regions. For example, the initializationdata place holders may be inserted in the beginning of the known datasequence. Herein, the size of the mobile service data that can beinserted in a data group may vary in accordance with the sizes of thetrellis initialization place holders or known data (or known data placeholders), MPEG header place holders, and RS parity place holders.

The output of the group formatter 304 is inputted to the datadeinterleaver 305. And, the data deinterleaver 305 deinterleaves data byperforming an inverse process of the data interleaver on the data andplace holders within the data group, which are then outputted to thepacket formatter 306. More specifically, when the data and place holderswithin the data group configured, as shown in FIG. 19A, aredeinterleaved by the data deinterleaver 305, the data group beingoutputted to the packet formatter 306 is configured to have thestructure shown in FIG. 19B.

The packet formatter 306 removes the main service data place holders andthe RS parity place holders that were allocated for the deinterleavingprocess from the deinterleaved data being inputted. Then, the packetformatter 306 groups the remaining portion and replaces the 4-byte MPEGheader place holder with an MPEG header having a null packet PID (or anunused PID from the main service data packet). Also, when the groupformatter 304 inserts known data place holders, the packet formatter 306may insert actual known data in the known data place holders, or maydirectly output the known data place holders without any modification inorder to make replacement insertion in a later process. Thereafter, thepacket formatter 306 identifies the data within the packet-formatteddata group, as described above, as a 188-byte unit mobile service datapacket (i.e., MPEG TS packet), which is then provided to the packetmultiplexer 240.

The packet multiplexer 240 multiplexes the mobile service data packetoutputted from the pre-processor 230 and the main service data packetoutputted from the packet jitter mitigator 220 in accordance with apre-defined multiplexing method. Then, the packet multiplexer 240outputs the multiplexed data packets to the data randomizer 251 of thepost-processor 250. Herein, the multiplexing method may vary inaccordance with various variables of the system design. One of themultiplexing methods of the packet formatter 240 consists of providing aburst section along a time axis, and, then, transmitting a plurality ofdata groups during a burst-on section within the burst section, andtransmitting only the main service data during the burst-off sectionwithin the burst section. Herein, the burst section indicates thesection starting from the beginning of the current burst until thebeginning of the next burst.

At this point, the main service data may be transmitted during theburst-on section. The packet multiplexer 240 refers to the transmissionparameter, such as information on the burst size or the burst period, soas to be informed of the number of data groups and the period of thedata groups included in a single burst. Herein, the mobile service dataand the main service data may co-exist in the burst-on section, and onlythe main service data may exist in the burst-off section. Therefore, amain data service section transmitting the main service data may existin both burst-on and burst-off sections. At this point, the main dataservice section within the burst-on section and the number of main dataservice packets included in the burst-off section may either bedifferent from one another or be the same.

When the mobile service data are transmitted in a burst structure, inthe receiving system receiving only the mobile service data turns thepower on only during the burst section, thereby receiving thecorresponding data. Alternatively, in the section transmitting only themain service data, the power is turned off so that the main service dataare not received in this section. Thus, the power consumption of thereceiving system may be reduced.

Detailed Embodiments of the RS Frame Structure and Packet Multiplexing

Hereinafter, detailed embodiments of the pre-processor 230 and thepacket multiplexer 240 will now be described. According to an embodimentof the present invention, the N value corresponding to the length of arow, which is included in the RS frame that is configured by the RSframe encoder 302, is set to 538. Accordingly, the RS frame encoder 302receives 538 transport stream (TS) packets so as to configure a first RSframe having the size of 538*187 bytes. Thereafter, as described above,the first RS frame is processed with a (235,187)-RS encoding process soas to configure a second RS frame having the size of 538*235 bytes.Finally, the second RS frame is processed with generating a 16-bitchecksum so as to configure a third RS frame having the sizes of540*235.

For example, it is assumed that the mobile service data that are to beinserted in regions A1 to A5 of region A are ½-rate encoded, and themobile service data that are to be inserted in regions B1 and B2 ofregion B are ¼-rate encoded by the block processor 303. And it isassumed that the mobile service data that are to be inserted in regionsA and B are the same kind of mobile service data.

Meanwhile, as shown in FIG. 19A, the sum of the number of bytes ofregions A1 to A5 of region A, in which ½-rate encoded mobile servicedata are to be inserted, among the plurality of regions within the datagroup is equal to 13024 bytes (=2428+2580+2772+2472+2772 bytes). Herein,the number of byte prior to performing the ½-rate encoding process isequal to 6512 (=13024/2). On the other hand, the sum of the number ofbytes of regions B1 and B2 of region B, in which ¼-rate encoded mobileservice data are to be inserted, among the plurality of regions withinthe data group is equal to 2280 bytes (=930+1350 bytes). Herein, thenumber of byte prior to performing the ¼-rate encoding process is equalto 570 (−2280/4).

In other words, when 7082 bytes of mobile service data are inputted tothe block processor 303, 6512 byte are expanded to 13024 bytes by being½-rate encoded, and 570 bytes are expanded to 2280 bytes by being ¼-rateencoded. Thereafter, the block processor 303 inserts the mobile servicedata expanded to 13024 bytes in regions A1 to A5 of region A and, also,inserts the mobile service data expanded to 2280 bytes in regions B1 andB2 of region B. Herein, the 7082 bytes of mobile service data beinginputted to the block processor 303 may be divided into an output of theRS frame encoder 302 and signaling information. In the presentinvention, among the 7082 bytes of mobile service data, 7050 bytescorrespond to the output of the RS frame encoder 302, and the remaining32 bytes correspond to the signaling information data. Then, ½-rateencoding or ¼-rate encoding is performed on the corresponding databytes.

Meanwhile, a RS frame being processed with RS encoding and CRC encodingfrom the RS frame encoder 302 is configured of 540*235 bytes, in otherwords, 126900 bytes. The 126900 bytes are divided by 7050-byte unitsalong the time axis, so as to produce 18 7050-byte units. Thereafter, a32-byte unit of signaling information data is added to the 7050-byteunit mobile service data being outputted from the RS frame encoder 302.Subsequently, the RS frame encoder 302 performs ½-rate encoding or¼-rate encoding on the corresponding data bytes, which are thenoutputted to the group formatter 304. Accordingly, the group formatter304 inserts the ½-rate encoded data in region A and the ¼-rate encodeddata in region B.

The process of deciding an N value that is required for configuring theRS frame from the RS frame encoder 302 will now be described in detail.More specifically, the size of the final RS frame (i.e., the third RSframe), which is RS encoded and CRC encoded from the RS frame encoder302, which corresponds to (N+2)*235 bytes should be allocated to Xnumber of groups, wherein X is an integer. Herein, in a single datagroup, 7050 data bytes prior to being encoded are allocated. Therefore,if the (N+2)*235 bytes are set to be the exact multiple of 7050(=30*235), the output data of the RS frame encoder 302 may beefficiently allocated to the data group. According to an embodiment ofthe present invention, the value of N is decided so that (N+2) becomes amultiple of 30. For example, in the present invention, N is equal to538, and (N+2) (=540) divided by 30 is equal to 18. This indicates thatthe mobile service data within one RS frame are processed with either½-rate encoding or ¼-rate encoding. The encoded mobile service data arethen allocated to 18 data groups.

FIG. 20 illustrates a process of dividing the RS frame according to thepresent invention. More specifically, the RS frame having the size of(N+2)*235 is divided into 30*235 byte blocks. Then, the divided blocksare mapped to a single group. In other words, the data of a block havingthe size of 30*235 bytes are processed with one of a ½-rate encodingprocess and a ¼-rate encoding process and are, then, inserted in a datagroup.

In another example, it is assumed that the mobile service data that areto be inserted in region C are ½-rate encoded by the block processor303, and that the mobile service data that are to be inserted in regionC correspond to a different type of mobile service data that areinserted in regions A and B. In this case, as shown in FIG. 19A, thetotal number of ½-rate encoded mobile service data bytes that are to beincluded in regions C1 to C3 of region C is equal to 4144 bytes (i.e.,4144=1272+1560+1312). In this case, the total number of mobile servicedata bytes prior to being ½-rate encoded is equal to 2072 bytes (i.e.,2072=4144/2). At this point, when it is assumed that 18 data groups aregrouped to form a RS frame, and that the mobile service data of the RSframe are inserted into the region C, the RS frame is configured of37296 bytes. Herein, the number of RS parity bytes P is set to be equalto 36 (i.e., P=36), and 2 CRC checksums are set to be included for eachrow.

Accordingly, a total of 165 188-byte mobile service data packets may betransmitted for each RS frame. In this case, 55 bytes may remain foreach RS frame of the region C within the data group. Remaining databytes may occur, when dividing each RS frame into a plurality of datagroups having the same size. More specifically, remaining data bytes mayoccur in particular regions in each RS frame depending upon the size ofthe RS frames, the size and number of divided data groups, the number ofmobile service data bytes that may be inserted into each data group, thecoding rate of the corresponding region, the number of RS parity bytes,whether or not a CRC checksum has been allocated, and, if any, thenumber of CRC checksums allocated.

When dividing the RS frame into a plurality of data groups having thesame size, and when remaining data bytes occur in the corresponding RSframe, K number of dummy bytes are added to the corresponding RS frame,wherein K is equal to the number of remaining data bytes within the RSframe. Then, the dummy byte-added RS frame is divided into a pluralityof data groups. This process is illustrated in FIG. 21. Morespecifically, FIG. 21 illustrates an example of processing K number ofremaining data bytes, which are produced by dividing the RS frame havingthe size of (N+2)*(187+P) bytes into M number of data groups havingequal sizes. In this case, as shown in FIG. 21( a), K number of dummybytes are added to the RS frame having the size of (N+2)*(187+P) bytes.Subsequently, the RS frame is read in row units, thereby being dividedinto M number of data groups, as shown in FIG. 21( b). At this point,each data group has the size of NoBytesPerGrp bytes. This may bedescribed by Equation 6 shown below.M×NoBytesPerGrp=(N+2)×(187+P)×K  Equation 6

Herein, NoBytesPerGrp indicates the number of bytes allocated for eachgroup (i.e., the Number of Bytes Per Group). More specifically, the sizecorresponding to the number of byte in one RS frame+K bytes is equal tothe size of the M number of data groups.

When the mobile service data are transmitted by using theabove-described method and transmission mode, the data randomizer 301 ofthe pre-processor 230 may receive the mobile service data packetsthrough a first mobile service data path and a second mobile servicedata path, to which data that are to be allocated to regions A and B areinputted. More specifically, 538 data packets are inputted to the firstmobile service data path, and 165 data packets are inputted to thesecond mobile service data path. In order to do so, a plurality of datarandomizers and RS frame encoders may be provided. Accordingly, the 538data packets being inputted to the first mobile service data path andthe 165 data packets being inputted to the second mobile service datapath are randomized by each respective data randomizer. Then, each RSframe encoder performs RS frame unit encoding and super frame unit rowpermutation processes on the inputted data packets. Thereafter, theprocessed data packets are divided back to RS frame units, thereby beinginputted to the block processor 303.

For example, the RS frame encoder encoding the data being inputtedthrough the first mobile service data path adds 48 parity bytes in acolumn direction to the corresponding RS frame. This RS frame encoderalso adds a 2-byte CRC checksum in a row direction to the correspondingRS frame. The RS frame encoder encoding the data being inputted throughthe second mobile service data path adds 36 parity bytes in a columndirection to the corresponding RS frame. This RS frame encoder also addsa 2-byte CRC checksum in a row direction to the corresponding RS frame.

The block processor 303 performs ½-rate encoding on the data that are tobe allocated to regions A and C. And, the block processor 303 performs¼-rate encoding on the data that are to be allocated to region B. Theblock processor 303 then outputs the encoded data to the group formatter304.

At this point, since 55 bytes remain in region C included in the datagroup for each RS frame, as described above, the block processor 303adds 55 bytes of dummy bytes to region C, once all data that are to beallocated to region C are inputted. Thereafter, the block processor 303½-rate encodes the processed data. Herein, the dummy bytes may be addedby the block processor 303, as described above, or may be added by anexternal block (not shown).

The group formatter 304 inserts (or allocates) the ½-rate or ¼-rateencoded and inputted mobile service data and known data (e.g., MPEGheader place holders, non-systematic RS parity place holders,initialization data place holders, etc.) to the respective regionswithin the data group shown in FIG. 19A. For example, the mobile servicedata that are inputted through the first mobile service data path andthen ½-rate or ¼-rate encoded are inserted in regions A and B. And, themobile service data that are inputted through the second mobile servicedata path and then ½-rate encoded are inserted in region C.

FIG. 22 illustrates detailed exemplary operations of the packetmultiplexer 240 according to an embodiment of the present invention.More specifically, the packet multiplexer 240 multiplexes data fieldsincluding a data group and data fields only including main service dataand outputs the randomized data to the data randomizer 251. According tothe present invention, the data fields including a data group aretransmitted to a burst-on section. And, the data fields including onlythe main service data are transmitted to a burst-off section. At thispoint, the burst-on section may also transmit the main service data.

FIG. 22 illustrates exemplary operations of a packet multiplexer fortransmitting the data group according to the present invention. Morespecifically, the packet multiplexer 240 multiplexes a field including adata group, in which the mobile service data and main service data aremixed with one another, and a field including only the main servicedata. Thereafter, the packet multiplexer 240 outputs the multiplexedfields to the data randomizer 251. At this point, in order to transmitthe RS frame having the size of 540*235 bytes, 18 data groups should betransmitted. Herein, each data group includes field synchronizationdata, as shown in FIG. 19A. Therefore, the 18 data groups aretransmitted during 18 field sections, and the section during which the18 data groups are being transmitted corresponds to the burst-onsection.

In each field within the burst-on section, a data group including fieldsynchronization data is multiplexed with main service data, which arethen outputted. For example, in the embodiment of the present invention,in each field within the burst-on section, a data group having the sizeof 118 segments is multiplexed with a set of main service data havingthe size of 194 segments. Referring to FIG. 22, during the burst-onsection (i.e., during the 18 field sections), a field including 18 datagroups is transmitted. Then, during the burst-off section that follows(i.e., during the 12 field sections), a field consisting only of themain service data is transmitted. Subsequently, during a subsequentburst-on section, 18 fields including 18 data groups are transmitted.And, during the following burst-off section, 12 fields consisting onlyof the main service data are transmitted.

Furthermore, in the present invention, the same type of data service maybe provided in the first burst-on section including the first 18 datagroups and in the second burst-on section including the next 18 datagroups. Alternatively, different types of data service may be providedin each burst-on section. For example, when it is assumed that differentdata service types are provided to each of the first burst-on sectionand the second burst-on section, and that the receiving system wishes toreceive only one type of data service, the receiving system turns thepower on only during the corresponding burst-on section including thedesired data service type so as to receive the corresponding 18 datafields. Then, the receiving system turns the power off during theremaining 42 field sections so as to prevent other data service typesfrom being received. Thus, the amount of power consumption of thereceiving system may be reduced. In addition, the receiving systemaccording to the present invention is advantageous in that one RS framemay be configured from the 18 data groups that are received during asingle burst-on section.

According to the present invention, the number of data groups includedin a burst-on section may vary based upon the size of the RS frame, andthe size of the RS frame varies in accordance with the value N. Morespecifically, by adjusting the value N, the number of data groups withinthe burst section may be adjusted. Herein, in an example of the presentinvention, the (235,187)-RS encoding process adjusts the value N duringa fixed state. Furthermore, the size of the mobile service data that canbe inserted in the data group may vary based upon the sizes of thetrellis initialization data or known data, the MPEG header, and the RSparity, which are inserted in the corresponding data group.

Meanwhile, since a data group including mobile service data in-betweenthe data bytes of the main service data during the packet multiplexingprocess, the shifting of the chronological position (or place) of themain service data packet becomes relative. Also, a system object decoder(i.e., MPEG decoder) for processing the main service data of thereceiving system, receives and decodes only the main service data andrecognizes the mobile service data packet as a null data packet.Therefore, when the system object decoder of the receiving systemreceives a main service data packet that is multiplexed with the datagroup, a packet jitter occurs.

At this point, since a multiple-level buffer for the video data existsin the system object decoder and the size of the buffer is relativelylarge, the packet jitter generated from the packet multiplexer 240 doesnot cause any serious problem in case of the video data. However, sincethe size of the buffer for the audio data is relatively small, thepacket jitter may cause considerable problem. More specifically, due tothe packet jitter, an overflow or underflow may occur in the buffer forthe main service data of the receiving system (e.g., the buffer for theaudio data). Therefore, the packet jitter mitigator 220 re-adjusts therelative position of the main service data packet so that the overflowor underflow does not occur in the system object decoder.

In the present invention, examples of repositioning places for the audiodata packets within the main service data in order to minimize theinfluence on the operations of the audio buffer will be described indetail. The packet jitter mitigator 220 repositions the audio datapackets in the main service data section so that the audio data packetsof the main service data can be as equally and uniformly aligned andpositioned as possible. The standard for repositioning the audio datapackets in the main service data performed by the packet jittermitigator 220 will now be described. Herein, it is assumed that thepacket jitter mitigator 220 knows the same multiplexing information asthat of the packet multiplexer 240, which is placed further behind thepacket jitter mitigator 220.

Firstly, if one audio data packet exists in the main service datasection (e.g., the main service data section positioned between two datagroups) within the burst-on section, the audio data packet is positionedat the very beginning of the main service data section. Alternatively,if two audio data packets exist in the corresponding data section, oneaudio data packet is positioned at the very beginning and the otheraudio data packet is positioned at the very end of the main service datasection. Further, if more than three audio data packets exist, one audiodata packet is positioned at the very beginning of the main service datasection, another is positioned at the very end of the main service datasection, and the remaining audio data packets are equally positionedbetween the first and last audio data packets. Secondly, during the mainservice data section placed immediately before the beginning of aburst-on section (i.e., during a burst-off section), the audio datapacket is placed at the very end of the corresponding section.

Thirdly, during a main service data section within the burst-off sectionafter the burst-on section, the audio data packet is positioned at thevery end of the main service data section. Finally, the data packetsother than audio data packets are positioned in accordance with theinputted order in vacant spaces (i.e., spaces that are not designatedfor the audio data packets). Meanwhile, when the positions of the mainservice data packets are relatively re-adjusted, associated programclock reference (PCR) values may also be modified accordingly. The PCRvalue corresponds to a time reference value for synchronizing the timeof the MPEG decoder. Herein, the PCR value is inserted in a specificregion of a TS packet and then transmitted.

In the example of the present invention, the packet jitter mitigator 220also performs the operation of modifying the PCR value. The output ofthe packet jitter mitigator 220 is inputted to the packet multiplexer240. As described above, the packet multiplexer 240 multiplexes the mainservice data packet outputted from the packet jitter mitigator 220 withthe mobile service data packet outputted from the pre-processor 230 intoa burst structure in accordance with a pre-determined multiplexing rule.Then, the packet multiplexer 240 outputs the multiplexed data packets tothe data randomizer 251 of the post-processor 250.

If the inputted data correspond to the main service data packet, thedata randomizer 251 performs the same randomizing process as that of theconventional randomizer. More specifically, the synchronization bytewithin the main service data packet is deleted. Then, the remaining 187data bytes are randomized by using a pseudo random byte generated fromthe data randomizer 251. Thereafter, the randomized data are outputtedto the RS encoder/non-systematic RS encoder 252.

On the other hand, if the inputted data correspond to the mobile servicedata packet, the data randomizer 251 may randomize only a portion of thedata packet. For example, if it is assumed that a randomizing processhas already been performed in advance on the mobile service data packetby the pre-processor 230, the data randomizer 251 deletes thesynchronization byte from the 4-byte MPEG header included in the mobileservice data packet and, then, performs the randomizing process only onthe remaining 3 data bytes of the MPEG header. Thereafter, therandomized data bytes are outputted to the RS encoder/non-systematic RSencoder 252. More specifically, the randomizing process is not performedon the remaining portion of the mobile service data excluding the MPEGheader. In other words, the remaining portion of the mobile service datapacket is directly outputted to the RS encoder/non-systematic RS encoder252 without being randomized. Also, the data randomizer 251 may or maynot perform a randomizing process on the known data (or known data placeholders) and the initialization data place holders included in themobile service data packet.

The RS encoder/non-systematic RS encoder 252 performs an RS encodingprocess on the data being randomized by the data randomizer 251 or onthe data bypassing the data randomizer 251, so as to add 20 bytes of RSparity data. Thereafter, the processed data are outputted to the datainterleaver 253. Herein, if the inputted data correspond to the mainservice data packet, the RS encoder/non-systematic RS encoder 252performs the same systematic RS encoding process as that of theconventional broadcasting system, thereby adding the 20-byte RS paritydata at the end of the 187-byte data. Alternatively, if the inputteddata correspond to the mobile service data packet, the RSencoder/non-systematic RS encoder 252 performs a non-systematic RSencoding process. At this point, the 20-byte RS parity data obtainedfrom the non-systematic RS encoding process are inserted in apre-decided parity byte place within the mobile service data packet.

The data interleaver 253 corresponds to a byte unit convolutionalinterleaver. The output of the data interleaver 253 is inputted to theparity replacer 254 and to the non-systematic RS encoder 255. Meanwhile,a process of initializing a memory within the trellis encoding module256 is primarily required in order to decide the output data of thetrellis encoding module 256, which is located after the parity replacer254, as the known data pre-defined according to an agreement between thereceiving system and the transmitting system. More specifically, thememory of the trellis encoding module 256 should first be initializedbefore the received known data sequence is trellis-encoded. At thispoint, the beginning portion of the known data sequence that is receivedcorresponds to the initialization data place holder and not to theactual known data. Herein, the initialization data place holder has beenincluded in the data by the group formatter within the pre-processor 230in an earlier process. Therefore, the process of generatinginitialization data and replacing the initialization data place holderof the corresponding memory with the generated initialization data arerequired to be performed immediately before the inputted known datasequence is trellis-encoded.

Additionally, a value of the trellis memory initialization data isdecided and generated based upon a memory status of the trellis encodingmodule 256. Further, due to the newly replaced initialization data, aprocess of newly calculating the RS parity and replacing the RS parity,which is outputted from the data interleaver 253, with the newlycalculated RS parity is required. Therefore, the non-systematic RSencoder 255 receives the mobile service data packet including theinitialization data place holders, which are to be replaced with theactual initialization data, from the data interleaver 253 and alsoreceives the initialization data from the trellis encoding module 256.

Among the inputted mobile service data packet, the initialization dataplace holders are replaced with the initialization data, and the RSparity data that are added to the mobile service data packet are removedand processed with non-systematic RS encoding. Thereafter, the new RSparity obtained by performing the non-systematic RS encoding process isoutputted to the parity replacer 255. Accordingly, the parity replacer255 selects the output of the data interleaver 253 as the data withinthe mobile service data packet, and the parity replacer 255 selects theoutput of the non-systematic RS encoder 255 as the RS parity. Theselected data are then outputted to the trellis encoding module 256.

Meanwhile, if the main service data packet is inputted or if the mobileservice data packet, which does not include any initialization dataplace holders that are to be replaced, is inputted, the parity replacer254 selects the data and RS parity that are outputted from the datainterleaver 253. Then, the parity replacer 254 directly outputs theselected data to the trellis encoding module 256 without anymodification. The trellis encoding module 256 converts the byte-unitdata to symbol units and performs a 12-way interleaving process so as totrellis-encode the received data. Thereafter, the processed data areoutputted to the synchronization multiplexer 260.

The synchronization multiplexer 260 inserts a field synchronizationsignal and a segment synchronization signal to the data outputted fromthe trellis encoding module 256 and, then, outputs the processed data tothe pilot inserter 271 of the transmission unit 270. Herein, the datahaving a pilot inserted therein by the pilot inserter 271 are modulatedby the modulator 272 in accordance with a pre-determined modulatingmethod (e.g., a VSB method). Thereafter, the modulated data aretransmitted to each receiving system though the radio frequency (RF)up-converter 273.

Block Processor

FIG. 23 illustrates a block diagram showing a structure of a blockprocessor according to the present invention. Herein, the blockprocessor includes a byte-bit converter 401, a symbol encoder 402, asymbol interleaver 403, and a symbol-byte converter 404. The byte-bitconverter 401 divides the mobile service data bytes that are inputtedfrom the RS frame encoder 112 into bits, which are then outputted to thesymbol encoder 402. The byte-bit converter 401 may also receivesignaling information including transmission parameters. The signalinginformation data bytes are also divided into bits so as to be outputtedto the symbol encoder 402. Herein, the signaling information includingtransmission parameters may be processed with the same data processingstep as that of the mobile service data. More specifically, thesignaling information may be inputted to the block processor 303 bypassing through the data randomizer 301 and the RS frame encoder 302.Alternatively, the signaling information may also be directly outputtedto the block processor 303 without passing though the data randomizer301 and the RS frame encoder 302.

The symbol encoder 402 corresponds to a G/H-rate encoder encoding theinputted data from G bits to H bits and outputting the data encoded atthe coding rate of G/H. According to the embodiment of the presentinvention, it is assumed that the symbol encoder 402 performs either acoding rate of ½ (also referred to as a ½-rate encoding process) or anencoding process at a coding rate of ¼ (also referred to as a ¼-rateencoding process). The symbol encoder 402 performs one of ½-rateencoding and ¼-rate encoding on the inputted mobile service data andsignaling information. Thereafter, the signaling information is alsorecognized as the mobile service data and processed accordingly.

In case of performing the ½-rate coding process, the symbol encoder 402receives 1 bit and encodes the received 1 bit to 2 bits (i.e., 1symbol). Then, the symbol encoder 402 outputs the processed 2 bits (or 1symbol). On the other hand, in case of performing the ¼-rate encodingprocess, the symbol encoder 402 receives 1 bit and encodes the received1 bit to 4 bits (i.e., 2 symbols). Then, the symbol encoder 402 outputsthe processed 4 bits (or 2 symbols).

FIG. 24 illustrates a detailed block diagram of the symbol encoder 402shown in FIG. 23. The symbol encoder 402 includes two delay units 501and 503 and three adders 502, 504, and 505. Herein, the symbol encoder402 encodes an input data bit U and outputs the coded bit U to 4 bits(u0 to u4). At this point, the data bit U is directly outputted asuppermost bit u0 and simultaneously encoded as lower bit u1u2u3 and thenoutputted. More specifically, the input data bit U is directly outputtedas the uppermost bit u0 and simultaneously outputted to the first andthird adders 502 and 505. The first adder 502 adds the input data bit Uand the output bit of the first delay unit 501 and, then, outputs theadded bit to the second delay unit 503. Then, the data bit delayed by apre-determined time (e.g., by 1 clock) in the second delay unit 503 isoutputted as lower bit u1 and simultaneously fed-back to the first delayunit 501. The first delay unit 501 delays the data bit fed-back from thesecond delay unit 503 by a pre-determined time (e.g., by 1 clock). Then,the first delay unit 501 outputs the delayed data bit to the first adder502 and the second adder 504. The second adder 504 adds the data bitsoutputted from the first and second delay units 501 and 503 as a lowerbit u2. The third adder 505 adds the input data bit U and the output ofthe second delay unit 503 and outputs the added data bit as a lower bitu3.

At this point, if the input data bit U corresponds to data encoded at a½-coding rate, the symbol encoder 402 configures a symbol with u1u0 bitsfrom the 4 output bits u0u1u2u3. Then, the symbol encoder 402 outputsthe newly configured symbol. Alternatively, if the input data bit Ucorresponds to data encoded at a ¼-coding rate, the symbol encoder 402configures and outputs a symbol with bits u1u0 and, then, configures andoutputs another symbol with bits u2u3. According to another embodimentof the present invention, if the input data bit U corresponds to dataencoded at a ¼-coding rate, the symbol encoder 402 may also configureand output a symbol with bits u1u0, and then repeat the process onceagain and output the corresponding bits. According to yet anotherembodiment of the present invention, the symbol encoder outputs all fouroutput bits U u0u1u2u3. Then, when using the ½-coding rate, the symbolinterleaver 403 located behind the symbol encoder 402 selects only thesymbol configured of bits u1u0 from the four output bits u0u1u2u3.Alternatively, when using the ¼-coding rate, the symbol interleaver 403may select the symbol configured of bits u1u0 and then select anothersymbol configured of bits u2u3. According to another embodiment, whenusing the ¼-coding rate, the symbol interleaver 403 may repeatedlyselect the symbol configured of bits u1u0.

The output of the symbol encoder 402 is inputted to the symbolinterleaver 403. Then, the symbol interleaver 403 performs blockinterleaving in symbol units on the data outputted from the symbolencoder 402. Any interleaver performing structural rearrangement (orrealignment) may be applied as the symbol interleaver 403 of the blockprocessor. However, in the present invention, a variable length symbolinterleaver that can be applied even when a plurality of lengths isprovided for the symbol, so that its order may be rearranged, may alsobe used.

FIG. 25 illustrates a symbol interleaver according to an embodiment ofthe present invention. Herein, the symbol interleaver according to theembodiment of the present invention corresponds to a variable lengthsymbol interleaver that may be applied even when a plurality of lengthsis provided for the symbol, so that its order may be rearranged.Particularly, FIG. 25 illustrates an example of the symbol interleaverwhen K=6 and L=8. Herein, K indicates a number of symbols that areoutputted for symbol interleaving from the symbol encoder 402. And, Lrepresents a number of symbols that are actually interleaved by thesymbol interleaver 403.

In the present invention, the symbol interleaver 403 should satisfy theconditions of L=2″ (wherein n is an integer) and of L≧K. If there is adifference in value between K and L, (L−K) number of null (or dummy)symbols is added, thereby creating an interleaving pattern. Therefore, Kbecomes a block size of the actual symbols that are inputted to thesymbol interleaver 403 in order to be interleaved. L becomes aninterleaving unit when the interleaving process is performed by aninterleaving pattern created from the symbol interleaver 403. Theexample of what is described above is illustrated in FIG. 25.

More specifically, FIG. 25( a) to FIG. 25( c) illustrate a variablelength interleaving process of a symbol interleaver shown in FIG. 23.The number of symbols outputted from the symbol encoder 402 in order tobe interleaved is equal to 6 (i.e., K=6). In other words, 6 symbols areoutputted from the symbol encoder 402 in order to be interleaved. And,the actual interleaving unit (L) is equal to 8 symbols. Therefore, asshown in FIG. 25( a), 2 symbols are added to the null (or dummy) symbol,thereby creating the interleaving pattern. Equation 7 shown belowdescribed the process of sequentially receiving K number of symbols, theorder of which is to be rearranged, and obtaining an L value satisfyingthe conditions of L=2″ (wherein n is an integer) and of L≧K, therebycreating the interleaving so as to realign (or rearrange) the symbolorder.

In relation to all places, wherein 0≦i≦L−1,P(i)={S×i×(i+1)/2} mod L  Equation 7

Herein, L≧K, L=2″, and n and S are integers. Referring to FIG. 25, it isassumed that S is equal to 89, and that L is equal to 8, and FIG. 25illustrates the created interleaving pattern and an example of theinterleaving process. As shown in FIG. 25( b), the order of K number ofinput symbols and (L−K) number of null symbols is rearranged by usingthe above-mentioned Equation 7. Then, as shown in FIG. 25( c), the nullbyte places are removed, so as to rearrange the order, by using Equation8 shown below. Thereafter, the symbol that is interleaved by therearranged order is then outputted to the symbol-byte converter.if P(i)>K−1, then P(i) place is removed and rearranged  Equation 8

Subsequently, the symbol-byte converter 404 converts to bytes the mobileservice data symbols, having the rearranging of the symbol ordercompleted and then outputted in accordance with the rearranged order,and thereafter outputs the converted bytes to the group formatter 304.

FIG. 26A illustrates a block diagram showing the structure of a blockprocessor according to another embodiment of the present invention.Herein, the block processor includes an interleaving unit 610 and ablock formatter 620. The interleaving unit 610 may include a byte-symbolconverter 611, a symbol-byte converter 612, a symbol interleaver 613,and a symbol-byte converter 614. Herein, the symbol interleaver 613 mayalso be referred to as a block interleaver.

The byte-symbol converter 611 of the interleaving unit 610 converts themobile service data X outputted in byte units from the RS frame encoder302 to symbol units. Then, the byte-symbol converter 611 outputs theconverted mobile service data symbols to the symbol-byte converter 612and the symbol interleaver 613. More specifically, the byte-symbolconverter 611 converts each 2 bits of the inputted mobile service databyte (=8 bits) to 1 symbol and outputs the converted symbols. This isbecause the input data of the trellis encoding module 256 consist ofsymbol units configured of 2 bits. The relationship between the blockprocessor 303 and the trellis encoding module 256 will be described indetail in a later process. At this point, the byte-symbol converter 611may also receive signaling information including transmissionparameters. Furthermore, the signaling information bytes may also bedivided into symbol units and then outputted to the symbol-byteconverter 612 and the symbol interleaver 613.

The symbol-byte converter 612 groups 4 symbols outputted from thebyte-symbol converter 611 so as to configure a byte. Thereafter, theconverted data bytes are outputted to the block formatter 620. Herein,each of the symbol-byte converter 612 and the byte-symbol converter 611respectively performs an inverse process on one another. Therefore, theyield of these two blocks is offset. Accordingly, as shown in FIG. 26B,the input data X bypass the byte-symbol converter 611 and thesymbol-byte converter 612 and are directly inputted to the blockformatter 620. More specifically, the interleaving unit 610 of FIG. 26Bhas a structure equivalent to that of the interleaving unit shown inFIG. 26A. Therefore, the same reference numerals will be used in FIG.26A and FIG. 26B.

The symbol interleaver 613 performs block interleaving in symbol unitson the data that are outputted from the byte-symbol converter 611.Subsequently, the symbol interleaver 613 outputs the interleaved data tothe symbol-byte converter 614. Herein, any type of interleaver that canrearrange the structural order may be used as the symbol interleaver 613of the present invention. In the example given in the present invention,a variable length interleaver that may be applied for symbols having awide range of lengths, the order of which is to be rearranged. Forexample, the symbol interleaver of FIG. 25 may also be used in the blockprocessor shown in FIG. 26A and FIG. 26B.

The symbol-byte converter 614 outputs the symbols having the rearrangingof the symbol order completed, in accordance with the rearranged order.Thereafter, the symbols are grouped to be configured in byte units,which are then outputted to the block formatter 620. More specifically,the symbol-byte converter 614 groups 4 symbols outputted from the symbolinterleaver 613 so as to configure a data byte. As shown in FIG. 27, theblock formatter 620 performs the process of aligning the output of eachsymbol-byte converter 612 and 614 within the block in accordance with aset standard. Herein, the block formatter 620 operates in associationwith the trellis encoding module 256.

More specifically, the block formatter 620 decides the output order ofthe mobile service data outputted from each symbol-byte converter 612and 614 while taking into consideration the place (or order) of the dataexcluding the mobile service data that are being inputted, wherein themobile service data include main service data, known data, RS paritydata, and MPEG header data.

According to the embodiment of the present invention, the trellisencoding module 256 is provided with trellis encoders. FIG. 28illustrates a block diagram showing the trellis encoding module 256according to the present invention. In the example shown in FIG. 28, 12identical trellis encoders are combined to the interleaver in order todisperse noise. Herein, each trellis encoder may be provided with apre-coder.

FIG. 29A illustrates the block processor 303 being concatenated with thetrellis encoding module 256. In the transmitting system, a plurality ofblocks actually exists between the pre-processor 230 including the blockprocessor 303 and the trellis encoding module 256, as shown in FIG. 3.Conversely, the receiving system considers the pre-processor 230 to beconcatenated with the trellis encoding module 256, thereby performingthe decoding process accordingly. However, the data excluding the mobileservice data that are being inputted to the trellis encoding module 256,wherein the mobile service data include main service data, known data,RS parity data, and MPEG header data, correspond to data that are addedto the blocks existing between the block processor 303 and the trellisencoding module 256. FIG. 293 illustrates an example of a data processor650 being positioned between the block processor 303 and the trellisencoding module 256, while taking the above-described instance intoconsideration.

Herein, when the interleaving unit 610 of the block processor 303performs a ½-rate encoding process, the interleaving unit 610 may beconfigured as shown in FIG. 26A (or FIG. 26B). Referring to FIG. 3, forexample, the data processor 650 may include a group formatter 304, adata deinterleaver 305, a packet formatter 306, a packet multiplexer240, and a post-processor 250, wherein the post-processor 250 includes adata randomizer 251, a RS encoder/non-systematic RS encoder 252, a datainterleaver 253, a parity replacer 254, and a non-systematic RS encoder255.

At this point, the trellis encoding module 256 symbolizes the data thatare being inputted so as to divide the symbolized data and to send thedivided data to each trellis encoder in accordance with a pre-definedmethod. Herein, one byte is converted into 4 symbols, each beingconfigured of 2 bits. Also, the symbols created from the single databyte are all transmitted to the same trellis encoder. Accordingly, eachtrellis encoder pre-codes an upper bit of the input symbol, which isthen outputted as the uppermost output bit C2. Alternatively, eachtrellis encoder trellis-encodes a lower bit of the input symbol, whichis then outputted as two output bits C1 and C0. The block formatter 620is controlled so that the data byte outputted from each symbol-byteconverter can be transmitted to different trellis encoders.

Hereinafter, the operation of the block formatter 620 will now bedescribed in detail with reference to FIG. 23 to FIG. 26. Referring toFIG. 26A, for example, the data byte outputted from the symbol-byteconverter 612 and the data byte outputted from the symbol-byte converter614 are inputted to different trellis encoders of the trellis encodingmodule 256 in accordance with the control of the block formatter 620.Hereinafter, the data byte outputted from the symbol-byte converter 612will be referred to as X, and the data byte outputted from thesymbol-byte converter 614 will be referred to as Y, for simplicity.Referring to FIG. 27( a), each number (i.e., 0 to 11) indicates thefirst to twelfth trellis encoders of the trellis encoding module 256,respectively.

In addition, the output order of both symbol-byte converters arearranged (or aligned) so that the data bytes outputted from thesymbol-byte converter 612 are respectively inputted to the 0^(th) to5^(th) trellis encoders (0 to 5) of the trellis encoding module 256, andthat the data bytes outputted from the symbol-byte converter 614 arerespectively inputted to the 6^(th) to 11^(th) trellis encoders (6 to11) of the trellis encoding module 256. Herein, the trellis encodershaving the data bytes outputted from the symbol-byte converter 612allocated therein, and the trellis encoders having the data bytesoutputted from the symbol-byte converter 614 allocated therein aremerely examples given to simplify the understanding of the presentinvention. Furthermore, according to an embodiment of the presentinvention, and assuming that the input data of the block processor 303correspond to a block configured of 12 bytes, the symbol-byte converter612 outputs 12 data bytes from X0 to X11, and the symbol-byte converter614 outputs 12 data bytes from Y0 to Y11.

FIG. 27( b) illustrates an example of data being inputted to the trellisencoding module 256. Particularly, FIG. 27( b) illustrates an example ofnot only the mobile service data but also the main service data and RSparity data being inputted to the trellis encoding module 256, so as tobe distributed to each trellis encoder. More specifically, the mobileservice data outputted from the block processor 303 pass through thegroup formatter 304, from which the mobile service data are mixed withthe main service data and RS parity data and then outputted, as shown inFIG. 27( a). Accordingly, each data byte is respectively inputted to thetrellis encoders in accordance with the positions (or places) within thedata group after being data-interleaved.

Herein, when the output data bytes X and Y of the symbol-byte converters612 and 614 are allocated to each respective trellis encoder, the inputof each trellis encoder may be configured as shown in FIG. 27( b). Morespecifically, referring to FIG. 27( b), the six mobile service databytes (X0 to X5) outputted from the symbol-byte converter 612 aresequentially allocated (or distributed) to the first to sixth trellisencoders (0 to 5) of the trellis encoding module 256. Also, the 2 mobileservice data bytes Y0 and Y1 outputted from the symbol-byte converter614 are sequentially allocated to the 7^(th) and 8^(th) trellis encoders(6 and 7) of the trellis encoding module 256. Thereafter, among the 5main service data bytes, 4 data bytes are sequentially allocated to the9^(th) and 12^(th) trellis encoders (8 to 11) of the trellis encodingmodule 256. Finally, the remaining 1 byte of the main service data byteis allocated once again to the first trellis encoder (0).

It is assumed that the mobile service data, the main service data, andthe RS parity data are allocated to each trellis encoder, as shown inFIG. 27( b). It is also assumed that, as described above, the input ofthe block processor 303 is configured of 12 bytes, and that 12 bytesfrom X0 to X11 are outputted from the symbol-byte converter 612, andthat 12 bytes from Y0 to Y11 are outputted from the symbol-byteconverter 614. In this case, as shown in FIG. 27( c), the blockformatter 620 arranges the data bytes that are to be outputted from thesymbol-byte converters 612 and 614 by the order of X0 to X5, Y0, Y1, X6to X10, Y2 to Y7, X11, and Y8 to Y11. More specifically, the trellisencoder that is to perform the encoding process is decided based uponthe position (or place) within the transmission frame in which each databyte is inserted. At this point, not only the mobile service data butalso the main service data, the MPEG header data, and the RS parity dataare also inputted to the trellis encoding module 256. Herein, it isassumed that, in order to perform the above-described operation, theblock formatter 620 is informed of (or knows) the information on thedata group format after the data-interleaving process.

FIG. 30 illustrates a block diagram of the block processor performing anencoding process at a coding rate of 1/N according to an embodiment ofthe present invention. Herein, the block processor includes (N−1) numberof symbol interleavers 741 to 74N−1, which are configured in a parallelstructure. More specifically, the block processor having the coding rateof 1/N consists of a total of N number of branches (or paths) includinga branch (or path), which is directly transmitted to the block formatter730. In addition, the symbol interleaver 741 to 74N−1 of each branch mayeach be configured of a different symbol interleaver. Furthermore, (N−1)number of symbol-byte converter 751 to 75N−1 each corresponding to each(N−1) number of symbol interleavers 741 to 74N−1 may be included at theend of each symbol interleaver, respectively. Herein, the output data ofthe (N−1) number of symbol-byte converter 751 to 75N−1 are also inputtedto the block formatter 730.

In the example of the present invention, N is equal to or smaller than12. If N is equal to 12, the block formatter 730 may align the outputdata so that the output byte of the 12^(th) symbol-byte converter 75N−1is inputted to the 12^(th) trellis encoder. Alternatively, if N is equalto 3, the block formatter 730 may arranged the output order, so that thedata bytes outputted from the symbol-byte converter 720 are inputted tothe 1^(st) to 4^(th) trellis encoders of the trellis encoding module256, and that the data bytes outputted from the symbol-byte converter751 are inputted to the 5^(th) to 8^(th) trellis encoders, and that thedata bytes outputted from the symbol-byte converter 752 are inputted tothe 9^(th) to 12^(th) trellis encoders. At this point, the order of thedata bytes outputted from each symbol-byte converter may vary inaccordance with the position within the data group of the data otherthan the mobile service data, which are mixed with the mobile servicedata that are outputted from each symbol-byte converter.

FIG. 31 illustrates a detailed block diagram showing the structure of ablock processor according to another embodiment of the presentinvention. Herein, the block formatter is removed from the blockprocessor so that the operation of the block formatter may be performedby a group formatter. More specifically, the block processor of FIG. 31may include a byte-symbol converter 810, symbol-byte converters 820 and840, and a symbol interleaver 830. In this case, the output of eachsymbol-byte converter 820 and 840 is inputted to the group formatter850.

Also, the block processor may obtain a desired coding rate by addingsymbol interleavers and symbol-byte converters. If the system designerwishes a coding rate of 1/N, the block processor needs to be providedwith a total of N number of branches (or paths) including a branch (orpath), which is directly transmitted to the block formatter 850, and(N−1) number of symbol interleavers and symbol-byte convertersconfigured in a parallel structure with (N−1) number of branches. Atthis point, the group formatter 850 inserts place holders ensuring thepositions (or places) for the MPEG header, the non-systematic RS parity,and the main service data. And, at the same time, the group formatter850 positions the data bytes outputted from each branch of the blockprocessor.

The number of trellis encoders, the number of symbol-byte converters,and the number of symbol interleavers proposed in the present inventionare merely exemplary. And, therefore, the corresponding numbers do notlimit the spirit or scope of the present invention. It is apparent tothose skilled in the art that the type and position of each data bytebeing allocated to each trellis encoder of the trellis encoding module256 may vary in accordance with the data group format. Therefore, thepresent invention should not be understood merely by the examples givenin the description set forth herein. The mobile service data that areencoded at a coding rate of 1/N and outputted from the block processor303 are inputted to the group formatter 304. Herein, in the example ofthe present invention, the order of the output data outputted from theblock formatter of the block processor 303 are aligned and outputted inaccordance with the position of the data bytes within the data group.

Signaling Information Processing

The transmitter 200 according to the present invention may inserttransmission parameters by using a plurality of methods and in aplurality of positions (or places), which are then transmitted to thereceiving system. For simplicity, the definition of a transmissionparameter that is to be transmitted from the transmitter to thereceiving system will now be described. The transmission parameterincludes data group information, region information within a data group,the number of RS frames configuring a super frame (i.e., a super framesize (SFS)), the number of RS parity data bytes (P) for each columnwithin the RS frame, whether or not a checksum, which is added todetermine the presence of an error in a row direction within the RSframe, has been used, the type and size of the checksum if the checksumis used (presently, 2 bytes are added to the CRC), the number of datagroups configuring one RS frame—since the RS frame is transmitted to oneburst section, the number of data groups configuring the one RS frame isidentical to the number of data groups within one burst (i.e., burstsize (BS)), a turbo code mode, and a RS code mode.

Also, the transmission parameter required for receiving a burst includesa burst period—herein, one burst period corresponds to a value obtainedby counting the number of fields starting from the beginning of acurrent burst until the beginning of a next burst, a positioning orderof the RS frames that are currently being transmitted within a superframe (i.e., a permuted frame index (PFI)) or a positioning order ofgroups that are currently being transmitted within a RS frame (burst)(i.e., a group index (GI)), and a burst size. Depending upon the methodof managing a burst, the transmission parameter also includes the numberof fields remaining until the beginning of the next burst (i.e., time tonext burst (TNB)). And, by transmitting such information as thetransmission parameter, each data group being transmitted to thereceiving system may indicate a relative distance (or number of fields)between a current position and the beginning of a next burst.

The information included in the transmission parameter corresponds toexamples given to facilitate the understanding of the present invention.Therefore, the proposed examples do not limit the scope or spirit of thepresent invention and may be easily varied or modified by anyone skilledin the art. According to the first embodiment of the present invention,the transmission parameter may be inserted by allocating a predeterminedregion of the mobile service data packet or the data group. In thiscase, the receiving system performs synchronization and equalization ona received signal, which is then decoded by symbol units. Thereafter,the packet deformatter may separate the mobile service data and thetransmission parameter so as to detect the transmission parameter.According to the first embodiment, the transmission parameter may beinserted from the group formatter 304 and then transmitted.

According to the second embodiment of the present invention, thetransmission parameter may be multiplexed with another type of data. Forexample, when known data are multiplexed with the mobile service data, atransmission parameter may be inserted, instead of the known data, in aplace (or position) where a known data byte is to be inserted.Alternatively, the transmission parameter may be mixed with the knowndata and then inserted in the place where the known data byte is to beinserted. According to the second embodiment, the transmission parametermay be inserted from the group formatter 304 or from the packetformatter 306 and then transmitted.

According to a third embodiment of the present invention, thetransmission parameter may be inserted by allocating a portion of areserved region within a field synchronization segment of a transmissionframe. In this case, since the receiving system may perform decoding ona receiving signal by symbol units before detecting the transmissionparameter, the transmission parameter having information on theprocessing methods of the block processor 303 and the group formatter304 may be inserted in a reserved field of a field synchronizationsignal. More specifically, the receiving system obtains fieldsynchronization by using a field synchronization segment so as to detectthe transmission parameter from a pre-decided position. According to thethird embodiment, the transmission parameter may be inserted from thesynchronization multiplexer 240 and then transmitted.

According to the fourth embodiment of the present invention, thetransmission parameter may be inserted in a layer (or hierarchicalregion) higher than a transport stream (TS) packet. In this case, thereceiving system should be able to receive a signal and process thereceived signal to a layer higher than the TS packet in advance. At thispoint, the transmission parameter may be used to certify thetransmission parameter of a currently received signal and to provide thetransmission parameter of a signal that is to be received in a laterprocess.

In the present invention, the variety of transmission parametersassociated with the transmission signal may be inserted and transmittedby using the above-described methods according to the first to fourthembodiment of the present invention. At this point, the transmissionparameter may be inserted and transmitted by using only one of the fourembodiments described above, or by using a selection of theabove-described embodiments, or by using all of the above-describedembodiments. Furthermore, the information included in the transmissionparameter may be duplicated and inserted in each embodiment.Alternatively, only the required information may be inserted in thecorresponding position of the corresponding embodiment and thentransmitted. Furthermore, in order to ensure robustness of thetransmission parameter, a block encoding process of a short cycle (orperiod) may be performed on the transmission parameter and, then,inserted in a corresponding region. The method for performing ashort-period block encoding process on the transmission parameter mayinclude, for example, Kerdock encoding, BCH encoding, RS encoding, andrepetition encoding of the transmission parameter. Also, a combinationof a plurality of block encoding methods may also be performed on thetransmission parameter.

The transmission parameters may be grouped to create a block code of asmall size, so as to be inserted in a byte place allocated within thedata group for signaling and then transmitted. However, in this case,the block code passes through the block decoded from the receiving endso as to obtain a transmission parameter value. Therefore, thetransmission parameters of the turbo code mode and the RS code mode,which are required for block decoding, should first be obtained.Accordingly, the transmission parameters associated with a particularmode may be inserted in a specific section of a known data region. And,in this case, a correlation of with a symbol may be used for a fasterdecoding process. The receiving system refers to the correlation betweeneach sequence and the currently received sequences, thereby determiningthe encoding mode and the combination mode.

Meanwhile, when the transmission parameter is inserted in the fieldsynchronization segment region or the known data region and thentransmitted, and when the transmission parameter has passed through thetransmission channel, the reliability of the transmission parameter isdeteriorated. Therefore, one of a plurality of pre-defined patterns mayalso be inserted in accordance with the corresponding transmissionparameter. Herein, the receiving system performs a correlationcalculation between the received signal and the pre-defined patterns soas to recognize the transmission parameter. For example, it is assumedthat a burst including 5 data groups is pre-decided as pattern A basedupon an agreement between the transmitting system and the receivingsystem. In this case, the transmitting system inserts and transmitspattern A, when the number of groups within the burst is equal to 5.Thereafter, the receiving system calculates a correlation between thereceived data and a plurality of reference patterns including pattern A,which was created in advance. At this point, if the correlation valuebetween the received data and pattern A is the greatest, the receiveddata indicates the corresponding parameter, and most particularly, thenumber of groups within the burst. At this point, the number of groupsmay be acknowledged as 5. Hereinafter, the process of inserting andtransmitting the transmission parameter will now be described accordingto first, second, and third embodiments of the present invention.

First Embodiment

FIG. 32 illustrates a schematic diagram of the group formatter 304receiving the transmission parameter and inserting the receivedtransmission parameter in region A of the data group according to thepresent invention. Herein, the group formatter 304 receives mobileservice data from the block processor 303. Conversely, the transmissionparameter is processed with at least one of a data randomizing process,a RS frame encoding process, and a block processing process, and maythen be inputted to the group formatter 304. Alternatively, thetransmission parameter may be directly inputted to the group formatter304 without being processed with any of the above-mentioned processes.In addition, the transmission parameter may be provided from the servicemultiplexer 100. Alternatively, the transmission parameter may also begenerated and provided from within the transmitter 200. The transmissionparameter may also include information required by the receiving systemin order to receive and process the data included in the data group. Forexample, the transmission parameter may include data group information,and multiplexing information.

The group formatter 304 inserts the mobile service data and transmissionparameter which are to be inputted to corresponding regions within thedata group in accordance with a rule for configuring a data group. Forexample, the transmission parameter passes through a block encodingprocess of a short period and is, then, inserted in region A of the datagroup. Particularly, the transmission parameter may be inserted in apre-arranged and arbitrary position (or place) within region A. If it isassumed that the transmission parameter has been block encoded by theblock processor 303, the block processor 303 performs the same dataprocessing operation as the mobile service data, more specifically,either a ½-rate encoding or ¼-rate encoding process on the signalinginformation including the transmission parameter. Thereafter, the blockprocessor 303 outputs the processed transmission parameter to the groupformatter 304. Thereafter, the signaling information is also recognizedas the mobile service data and processed accordingly.

FIG. 33 illustrates a block diagram showing an example of the blockprocessor receiving the transmission parameter and processing thereceived transmission parameter with the same process as the mobileservice data. Particularly, FIG. 33 illustrates an example showing thestructure of FIG. 23 further including a signaling information provider411 and multiplexer 412. More specifically, the signaling informationprovider 411 outputs the signaling information including thetransmission parameter to the multiplexer 412. The multiplexer 412multiplexes the signaling information and the output of the RS frameencoder 302. Then, the multiplexer 412 outputs the multiplexed data tothe byte-bit converter 401.

The byte-bit converter 401 divides the mobile service data bytes orsignaling information byte outputted from the multiplexer 412 into bits,which are then outputted to the symbol encoder 402. The subsequentoperations are identical to those described in FIG. 23. Therefore, adetailed description of the same will be omitted for simplicity. If anyof the detailed structures of the block processor 303 shown in FIG. 26A,FIG. 26B, FIG. 29A, FIG. 29B, FIG. 30, and FIG. 31, the signalinginformation provider 411 and the multiplexer 412 may be provided behindthe byte-symbol converter.

Second Embodiment

Meanwhile, when known data generated from the group formatter inaccordance with a pre-decided rule are inserted in a correspondingregion within the data group, a transmission parameter may be insertedin at least a portion of a region, where known data may be inserted,instead of the known data. For example, when a long known data sequenceis inserted at the beginning of region A within the data group, atransmission parameter may be inserted in at least a portion of thebeginning of region A instead of the known data. A portion of the knowndata sequence that is inserted in the remaining portion of region A,excluding the portion in which the transmission parameter is inserted,may be used to detect a starting point of the data group by thereceiving system. Alternatively, another portion of region A may be usedfor channel equalization by the receiving system.

In addition, when the transmission parameter is inserted in the knowndata region instead of the actual known data. The transmission parametermay be block encoded in short periods and then inserted. Also, asdescribed above, the transmission parameter may also be inserted basedupon a pre-defined pattern in accordance with the transmissionparameter. If the group formatter 304 inserts known data place holdersin a region within the data group, wherein known data may be inserted,instead of the actual known data, the transmission parameter may beinserted by the packet formatter 306. More specifically, when the groupformatter 304 inserts the known data place holders, the packet formatter306 may insert the known data instead of the known data place holders.Alternatively, when the group formatter 304 inserts the known data, theknown data may be directly outputted without modification.

FIG. 34 illustrates a block diagram showing the structure of a packetformatter 306 being expanded so that the packet formatter 306 can insertthe transmission parameter according to an embodiment of the presentinvention. More specifically, the structure of the packet formatter 306further includes a known data generator 351 and a signaling multiplexer352. Herein, the transmission parameter that is inputted to thesignaling multiplexer 352 may include information on the length of acurrent burst, information indicating a starting point of a next burst,positions in which the groups within the burst exist and the lengths ofthe groups, information on the time from the current group and the nextgroup within the burst, and information on known data.

The signaling multiplexer 352 selects one of the transmission parameterand the known data generated from the known data generator 351 and,then, outputs the selected data to the packet formatter 306. The packetformatter 306 inserts the known data or transmission parameter outputtedfrom the signaling multiplexer 352 into the known data place holdersoutputted from the data interleaver 305. Then, the packet formatter 306outputs the processed data. More specifically, the packet formatter 306inserts a transmission parameter in at least a portion of the known dataregion instead of the known data, which is then outputted. For example,when a known data place holder is inserted at a beginning portion ofregion A within the data group, a transmission parameter may be insertedin a portion of the known data place holder instead of the actual knowndata.

Also, when the transmission parameter is inserted in the known dataplace holder instead of the known data, the transmission parameter maybe block encoded in short periods and inserted. Alternatively, apre-defined pattern may be inserted in accordance with the transmissionparameter. More specifically, the signaling multiplexer 352 multiplexesthe known data and the transmission parameter (or the pattern defined bythe transmission parameter) so as to configure a new known datasequence. Then, the signaling multiplexer 352 outputs the newlyconfigured known data sequence to the packet formatter 306. The packetformatter 306 deletes the main service data place holder and RS parityplace holder from the output of the data interleaver 305, and creates amobile service data packet of 188 bytes by using the mobile servicedata, MPEG header, and the output of the signaling multiplexer. Then,the packet formatter 306 outputs the newly created mobile service datapacket to the packet multiplexer 240.

In this case, the region A of each data group has a different known datapattern. Therefore, the receiving system separates only the symbol in apre-arranged section of the known data sequence and recognizes theseparated symbol as the transmission parameter. Herein, depending uponthe design of the transmitting system, the known data may be inserted indifferent blocks, such as the packet formatter 306, the group formatter304, or the block processor 303. Therefore, a transmission parameter maybe inserted instead of the known data in the block wherein the knowndata are to be inserted.

According to the second embodiment of the present invention, atransmission parameter including information on the processing method ofthe block processor 303 may be inserted in a portion of the known dataregion and then transmitted. In this case, a symbol processing methodand position of the symbol for the actual transmission parameter symbolare already decided. Also, the position of the transmission parametersymbol should be positioned so as to be transmitted or received earlierthan any other data symbols that are to be decoded. Accordingly, thereceiving system may detect the transmission symbol before the datasymbol decoding process, so as to use the detected transmission symbolfor the decoding process.

Third Embodiment

Meanwhile, the transmission parameter may also be inserted in the fieldsynchronization segment region and then transmitted. FIG. 35 illustratesa block diagram showing the synchronization multiplexer being expandedin order to allow the transmission parameter to be inserted in the fieldsynchronization segment region. Herein, a signaling multiplexer 261 isfurther included in the synchronization multiplexer 260. Thetransmission parameter of the general VSB method is configured of 2fields. More specifically, each field is configured of one fieldsynchronization segment and 312 data segments. Herein, the first 4symbols of a data segment correspond to the segment synchronizationportion, and the first data segment of each field corresponds to thefield synchronization portion.

One field synchronization signal is configured to have the length of onedata segment. The data segment synchronization pattern exists in thefirst 4 symbols, which are then followed by pseudo random sequences PN511, PN 63, PN 63, and PN 63. The next 24 symbols include informationassociated with the VSB mode. Additionally, the 24 symbols that includeinformation associated with the VSB mode are followed by the remaining104 symbols, which are reserved symbols. Herein, the last 12 symbols ofa previous segment are copied and positioned as the last 12 symbols inthe reserved region. In other words, only the 92 symbols in the fieldsynchronization segment are the symbols that correspond to the actualreserved region.

Therefore, the signaling multiplexer 261 multiplexes the transmissionparameter with an already-existing field synchronization segment symbol,so that the transmission parameter can be inserted in the reservedregion of the field synchronization segment. Then, the signalingmultiplexer 261 outputs the multiplexed transmission parameter to thesynchronization multiplexer 260. The synchronization multiplexer 260multiplexes the segment synchronization symbol, the data symbols, andthe new field synchronization segment outputted from the signalingmultiplexer 261, thereby configuring a new transmission frame. Thetransmission frame including the field synchronization segment, whereinthe transmission parameter is inserted, is outputted to the transmissionunit 270. At this point, the reserved region within the fieldsynchronization segment for inserting the transmission parameter maycorrespond to a portion of or the entire 92 symbols of the reservedregion. Herein, the transmission parameter being inserted in thereserved region may, for example, include information identifying thetransmission parameter as the main service data, the mobile servicedata, or a different type of mobile service data.

If the information on the processing method of the block processor 303is transmitted as a portion of the transmission parameter, and when thereceiving system wishes to perform a decoding process corresponding tothe block processor 303, the receiving system should be informed of suchinformation on the block processing method in order to perform thedecoding process. Therefore, the information on the processing method ofthe block processor 303 should already be known prior to the blockdecoding process. Accordingly, as described in the third embodiment ofthe present invention, when the transmission parameter having theinformation on the processing method of the block processor 303 (and/orthe group formatter 304) is inserted in the reserved region of the fieldsynchronization signal and then transmitted, the receiving system iscapable of detecting the transmission parameter prior to performing theblock decoding process on the received signal.

Receiving System

FIG. 36 illustrates a block diagram showing a structure of a digitalbroadcast receiving system according to the present invention. Thedigital broadcast receiving system of FIG. 36 uses known datainformation, which is inserted in the mobile service data section and,then, transmitted by the transmitting system, so as to perform carriersynchronization recovery, frame synchronization recovery, and channelequalization, thereby enhancing the receiving performance. Referring toFIG. 36, the digital broadcast receiving system includes a tuner 901, ademodulator 902, an equalizer 903, a known data detector 904, a blockdecoder 905, a data deformatter 906, a RS frame decoder 907, aderandomizer 908, a data deinterleaver 909, a RS decoder 910, and a dataderandomizer 911. Herein, for simplicity of the description of thepresent invention, the data deformatter 906, the RS frame decoder 907,and the derandomizer 908 will be collectively referred to as a mobileservice data processing unit. And, the data deinterleaver 909, the RSdecoder 910, and the data derandomizer 911 will be collectively referredto as a main service data processing unit.

More specifically, the tuner 901 tunes a frequency of a particularchannel and down-converts the tuned frequency to an intermediatefrequency (IF) signal. Then, the tuner 901 outputs the down-converted IFsignal to the demodulator 902 and the known data detector 904. Thedemodulator 902 performs self gain control, carrier recovery, and timingrecovery processes on the inputted IF signal, thereby modifying the IFsignal to a baseband signal. Then, the demodulator 902 outputs the newlycreated baseband signal to the equalizer 903 and the known data detector904. The equalizer 903 compensates the distortion of the channelincluded in the demodulated signal and then outputs theerror-compensated signal to the block decoder 905.

At this point, the known data detector 904 detects the known sequenceplace inserted by the transmitting end from the input/output data of thedemodulator 902 (i.e., the data prior to the demodulation process or thedata after the demodulation process). Thereafter, the place informationalong with the symbol sequence of the known data, which are generatedfrom the detected place, is outputted to the demodulator 902 and theequalizer 903. Also, the known data detector 904 outputs a set ofinformation to the block decoder 905. This set of information is used toallow the block decoder 905 of the receiving system to identify themobile service data that are processed with additional encoding from thetransmitting system and the main service data that are not processedwith additional encoding. In addition, although the connection status isnot shown in FIG. 36, the information detected from the known datadetector 904 may be used throughout the entire receiving system and mayalso be used in the data deformatter 906 and the RS frame decoder 907.The demodulator 902 uses the known data symbol sequence during thetiming and/or carrier recovery, thereby enhancing the demodulatingperformance. Similarly, the equalizer 903 uses the known data so as toenhance the equalizing performance. Moreover, the decoding result of theblock decoder 905 may be fed-back to the equalizer 903, therebyenhancing the equalizing performance.

The equalizer 903 may perform channel equalization by using a pluralityof methods. An example of estimating a channel impulse response (CIR) soas to perform channel equalization will be given in the description ofthe present invention. Most particularly, an example of estimating theCIR in accordance with each region within the data group, which ishierarchically divided and transmitted from the transmitting system, andapplying each CIR differently will also be described herein.Furthermore, by using the known data, the place and contents of which isknown in accordance with an agreement between the transmitting systemand the receiving system, and the field synchronization data, so as toestimate the CIR, the present invention may be able to perform channelequalization with more stability.

Herein, the data group that is inputted for the equalization process isdivided into regions A to C, as shown in FIG. 19A. More specifically, inthe example of the present invention, each region A, B, and C arefurther divided into regions A1 to A5, regions B1 and B2, and regions C1to C3, respectively. Referring to FIG. 19A, the CIR that is estimatedfrom the field synchronization data in the data structure is referred toas CIR_FS. Alternatively, the CIRs that are estimated from each of the 5known data sequences existing in region A are sequentially referred toas CIR_N0, CIR_N1, CIR_N2, CIR_N3, and CIR_N4.

As described above, the present invention uses the CIR estimated fromthe field synchronization data and the known data sequences in order toperform channel equalization on data within the data group. At thispoint, each of the estimated CIRs may be directly used in accordancewith the characteristics of each region within the data group.Alternatively, a plurality of the estimated CIRs may also be eitherinterpolated or extrapolated so as to create a new CIR, which is thenused for the channel equalization process.

Herein, when a value F(A) of a function F(x) at a particular point A anda value F(B) of the function F(x) at another particular point B areknown, interpolation refers to estimating a function value of a pointwithin the section between points A and B. Linear interpolationcorresponds to the simplest form among a wide range of interpolationoperations. The linear interpolation described herein is merelyexemplary among a wide range of possible interpolation methods. And,therefore, the present invention is not limited only to the examples setforth herein.

Alternatively, when a value F(A) of a function F(x) at a particularpoint A and a value F(B) of the function F(x) at another particularpoint B are known, extrapolation refers to estimating a function valueof a point outside of the section between points A and B. Linearextrapolation is the simplest form among a wide range of extrapolationoperations. Similarly, the linear extrapolation described herein ismerely exemplary among a wide range of possible extrapolation methods.And, therefore, the present invention is not limited only to theexamples set forth herein.

More specifically, in case of region C1, any one of the CIR_N4 estimatedfrom a previous data group, the CIR_FS estimated from the current datagroup that is to be processed with channel equalization, and a new CIRgenerated by extrapolating the CIR_FS of the current data group and theCIR_N0 may be used to perform channel equalization. Alternatively, incase of region B1, a variety of methods may be applied as described inthe case for region C1. For example, a new CIR created by linearlyextrapolating the CIR_FS estimated from the current data group and theCIR_N0 may be used to perform channel equalization. Also, the CIR_FSestimated from the current data group may also be used to performchannel equalization. Finally, in case of region A1, a new CIR may becreated by interpolating the CIR_FS estimated from the current datagroup and CIR_N0, which is then used to perform channel equalization.Furthermore, any one of the CIR_FS estimated from the current data groupand CIR_N0 may be used to perform channel equalization.

In case of regions A2 to A5, CIR_N(i−1) estimated from the current datagroup and CIR_N(i) may be interpolated to create a new CIR and use thenewly created CIR to perform channel equalization. Also, any one of theCIR_N(i−1) estimated from the current data group and the CIR_N(i) may beused to perform channel equalization. Alternatively, in case of regionsB2, C2, and C3, CIR_N3 and CIR_N4 both estimated from the current datagroup may be extrapolated to create a new CIR, which is then used toperform the channel equalization process. Furthermore, the CIR_N4estimated from the current data group may be used to perform the channelequalization process. Accordingly, an optimum performance may beobtained when performing channel equalization on the data inserted inthe data group. The methods of obtaining the CIRs required forperforming the channel equalization process in each region within thedata group, as described above, are merely examples given to facilitatethe understanding of the present invention. A wider range of methods mayalso be used herein. And, therefore, the present invention will not onlybe limited to the examples given in the description set forth herein.

Meanwhile, if the data being inputted to the block decoder 905 afterbeing channel equalized from the equalizer 903 correspond to the mobileservice data having additional encoding and trellis encoding performedthereon by the transmitting system, trellis decoding and additionaldecoding processes are performed on the inputted data as inverseprocesses of the transmitting system. Alternatively, if the data beinginputted to the block decoder 905 correspond to the main service datahaving only trellis encoding performed thereon, and not the additionalencoding, only the trellis decoding process is performed on the inputteddata as the inverse process of the transmitting system. The data groupdecoded by the block decoder 905 is inputted to the data deformatter906, and the main service data are inputted to the data deinterleaver909.

According to another embodiment, the main data may also bypass the blockdecoder 905 so as to be directly inputted to the data deinterleaver 909.In this case, a trellis decoder for the main service data should beprovided before the data deinterleaver 909. When the block decoder 905outputs the data group to the data deformatter 906, the known data,trellis initialization data, and MPEG header, which are inserted in thedata group, and the RS parity, which is added by the RSencoder/non-systematic RS encoder or non-systematic RS encoder of thetransmitting system, are removed. Then, the processed data are outputtedto the data deformatter 906. Herein, the removal of the data may beperformed before the block decoding process, or may be performed duringor after the block decoding process. If the transmitting system includessignaling information in the data group upon transmission, the signalinginformation is outputted to the data deformatter 906.

More specifically, if the inputted data correspond to the main servicedata, the block decoder 905 performs Viterbi decoding on the inputteddata so as to output a hard decision value or to perform a hard-decisionon a soft decision value, thereby outputting the result. Meanwhile, ifthe inputted data correspond to the mobile service data, the blockdecoder 905 outputs a hard decision value or a soft decision value withrespect to the inputted mobile service data. In other words, if theinputted data correspond to the mobile service data, the block decoder905 performs a decoding process on the data encoded by the blockprocessor and trellis encoding module of the transmitting system.

At this point, the RS frame encoder of the pre-processor included in thetransmitting system may be viewed as an external code. And, the blockprocessor and the trellis encoder may be viewed as an internal code. Inorder to maximize the performance of the external code when decodingsuch concatenated codes, the decoder of the internal code should outputa soft decision value. Therefore, the block decoder 905 may output ahard decision value on the mobile service data. However, when required,it may be more preferable for the block decoder 905 to output a softdecision value.

Meanwhile, the data deinterleaver 909, the RS decoder 910, and thederandomizer 911 are blocks required for receiving the main servicedata. Therefore, the above-mentioned blocks may not be required in thestructure of a digital broadcast receiving system that only receives themobile service data. The data deinterleaver 909 performs an inverseprocess of the data interleaver included in the transmitting system. Inother words, the data deinterleaver 909 deinterleaves the main servicedata outputted from the block decoder 905 and outputs the deinterleavedmain service data to the RS decoder 910. The RS decoder 910 performs asystematic RS decoding process on the deinterleaved data and outputs theprocessed data to the derandomizer 911. The derandomizer 911 receivesthe output of the RS decoder 910 and generates a pseudo random data byteidentical to that of the randomizer included in the digital broadcasttransmitting system. Thereafter, the derandomizer 911 performs a bitwiseexclusive OR (XOR) operation on the generated pseudo random data byte,thereby inserting the MPEG synchronization bytes to the beginning ofeach packet so as to output the data in 188-byte main service datapacket units.

Meanwhile, the data being outputted from the block decoder 905 to thedata deformatter 906 are inputted in the form of a data group. At thispoint, the data deformatter 906 already knows the structure of the datathat are to be inputted and is, therefore, capable of identifying thesignaling information, which includes the system information, and themobile service data from the data group. Thereafter, the datadeformatter 906 outputs the identified signaling information to a blockfor processing signaling information (not shown) and outputs theidentified mobile service data to the RS frame decoder 907. Morespecifically, the RS frame decoder 907 receives only the RS encoded andCRC encoded mobile service data that are transmitted from the datadeformatter 906.

The RS frame encoder 907 performs an inverse process of the RS frameencoder included in the transmitting system so as to correct the errorwithin the RS frame. Then, the RS frame decoder 907 adds the 1-byte MPEGsynchronization service data packet, which had been removed during theRS frame encoding process, to the error-corrected mobile service datapacket. Thereafter, the processed data packet is outputted to thederandomizer 908. The operation of the RS frame decoder 907 will bedescribed in detail in a later process. The derandomizer 908 performs aderandomizing process, which corresponds to the inverse process of therandomizer included in the transmitting system, on the received mobileservice data. Thereafter, the derandomized data are outputted, therebyobtaining the mobile service data transmitted from the transmittingsystem. Hereinafter, detailed operations of the RS frame decoder 907will now be described.

FIG. 37 illustrates a series of exemplary step of an error correctiondecoding process of the RS frame decoder 907 according to the presentinvention. More specifically, the RS frame decoder 907 groups mobileservice data bytes received from the data deformatter 906 so as toconfigure an RS frame. The mobile service data correspond to data RSencoded and CRC encoded from the transmitting system. FIG. 37( a)illustrates an example of configuring the RS frame. More specifically,the transmitting system divided the RS frame having the size of(N+2)*235 to 30*235 byte blocks. When it is assumed that each of thedivided mobile service data byte blocks is inserted in each data groupand then transmitted, the receiving system also groups the 30*235 mobileservice data byte blocks respectively inserted in each data group,thereby configuring an RS frame having the size of (N+2)*235. Forexample, when it is assumed that an RS frame is divided into 18 30*235byte blocks and transmitted from a burst section, the receiving systemalso groups the mobile service data bytes of 18 data groups within thecorresponding burst section, so as to configure the RS frame.Furthermore, when it is assumed that N is equal to 538 (i.e., N=538),the RS frame decoder 907 may group the mobile service data bytes withinthe 18 data groups included in a burst so as to configure a RS framehaving the size of 540*235 bytes.

Herein, when it is assumed that the block decoder 905 outputs a softdecision value for the decoding result, the RS frame decoder 907 maydecide the ‘0’ and ‘1’ of the corresponding bit by using the codes ofthe soft decision value. 8 bits that are each decided as described aboveare grouped to create 1 data byte. If the above-described process isperformed on all soft decision values of the 18 data groups included ina single burst, the RS frame having the size of 540*235 bytes may beconfigured. Additionally, the present invention uses the soft decisionvalue not only to configure the RS frame but also to configure areliability map. Herein, the reliability map indicates the reliabilityof the corresponding data byte, which is configured by grouping 8 bits,the 8 bits being decided by the codes of the soft decision value.

For example, when the absolute value of the soft decision value exceedsa pre-determined threshold value, the value of the corresponding bit,which is decided by the code of the corresponding soft decision value,is determined to be reliable. Conversely, when the absolute value of thesoft decision value does not exceed the pre-determined threshold value,the value of the corresponding bit is determined to be unreliable.Thereafter, if even a single bit among the 8 bits, which are decided bythe codes of the soft decision value and group to configure 1 data byte,is determined to be unreliable, the corresponding data byte is marked onthe reliability map as an unreliable data byte.

Herein, determining the reliability of 1 data byte is only exemplary.More specifically, when a plurality of data bytes (e.g., at least 4 databytes) are determined to be unreliable, the corresponding data bytes mayalso be marked as unreliable data bytes within the reliability map.Conversely, when all of the data bits within the 1 data byte aredetermined to be reliable (i.e., when the absolute value of the softdecision values of all 8 bits included in the 1 data byte exceed thepredetermined threshold value), the corresponding data byte is marked tobe a reliable data byte on the reliability map. Similarly, when aplurality of data bytes (e.g., at least 4 data bytes) are determined tobe reliable, the corresponding data bytes may also be marked as reliabledata bytes within the reliability map. The numbers proposed in theabove-described example are merely exemplary and, therefore, do notlimit the scope or spirit of the present invention.

The process of configuring the RS frame and the process of configuringthe reliability map both using the soft decision value may be performedat the same time. Herein, the reliability information within thereliability map is in a one-to-one correspondence with each byte withinthe RS frame. For example, if a RS frame has the size of 540*235 bytes,the reliability map is also configured to have the size of 540*235bytes. FIG. 37( a′) illustrates the process steps of configuring thereliability map according to the present invention. Meanwhile, if a RSframe is configured to have the size of (N+2)*235 bytes, the RS framedecoder 907 performs a CRC syndrome checking process on thecorresponding RS frame, thereby verifying whether any error has occurredin each row. Subsequently, as shown in FIG. 37( b), a 2-byte checksum isremoved to configure an RS frame having the size of N*235 bytes. Herein,the presence (or existence) of an error is indicated on an error flagcorresponding to each row. Similarly, since the portion of thereliability map corresponding to the CRC checksum has hardly anyapplicability, this portion is removed so that only N*235 number of thereliability information bytes remain, as shown in FIG. 37( b′).

After performing the CRC syndrome checking process, the RS frame decoder907 performs RS decoding in a column direction. Herein, a RS erasurecorrection process may be performed in accordance with the number of CRCerror flags. More specifically, as shown in FIG. 37( c), the CRC errorflag corresponding to each row within the RS frame is verified.Thereafter, the RS frame decoder 907 determines whether the number ofrows having a CRC error occurring therein is equal to or smaller thanthe maximum number of errors on which the RS erasure correction may beperformed, when performing the RS decoding process in a columndirection. The maximum number of errors corresponds to a number ofparity bytes inserted when performing the RS encoding process. In theembodiment of the present invention, it is assumed that 48 parity byteshave been added to each column.

If the number of rows having the CRC errors occurring therein is smallerthan or equal to the maximum number of errors (i.e., 48 errors accordingto this embodiment) that can be corrected by the RS erasure decodingprocess, a (235,187)-RS erasure decoding process is performed in acolumn direction on the RS frame having 235 N-byte rows, as shown inFIG. 37( d). Thereafter, as shown in FIG. 37( f), the 48-byte paritydata that have been added at the end of each column are removed.Conversely, however, if the number of rows having the CRC errorsoccurring therein is greater than the maximum number of errors (i.e., 48errors) that can be corrected by the RS erasure decoding process, the RSerasure decoding process cannot be performed. In this case, the errormay be corrected by performing a general RS decoding process. Inaddition, the reliability map, which has been created based upon thesoft decision value along with the RS frame, may be used to furtherenhance the error correction ability (or performance) of the presentinvention.

More specifically, the RS frame decoder 907 compares the absolute valueof the soft decision value of the block decoder 905 with thepre-determined threshold value, so as to determine the reliability ofthe bit value decided by the code of the corresponding soft decisionvalue. Also, 8 bits, each being determined by the code of the softdecision value, are grouped to form 1 data byte. Accordingly, thereliability information on this 1 data byte is indicated on thereliability map. Therefore, as shown in FIG. 37( e), even though aparticular row is determined to have an error occurring therein basedupon a CRC syndrome checking process on the particular row, the presentinvention does not assume that all bytes included in the row have errorsoccurring therein. The present invention refers to the reliabilityinformation of the reliability map and sets only the bytes that havebeen determined to be unreliable as erroneous bytes. In other words,with disregard to whether or not a CRC error exists within thecorresponding row, only the bytes that are determined to be unreliablebased upon the reliability map are set as erasure points.

According to another method, when it is determined that CRC errors areincluded in the corresponding row, based upon the result of the CRCsyndrome checking result, only the bytes that are determined by thereliability map to be unreliable are set as errors. More specifically,only the bytes corresponding to the row that is determined to haveerrors included therein and being determined to be unreliable based uponthe reliability information, are set as the erasure points. Thereafter,if the number of error points for each column is smaller than or equalto the maximum number of errors (i.e., 48 errors) that can be correctedby the RS erasure decoding process, an RS erasure decoding process isperformed on the corresponding column. Conversely, if the number oferror points for each column is greater than the maximum number oferrors (i.e., 48 errors) that can be corrected by the RS erasuredecoding process, a general decoding process is performed on thecorresponding column.

More specifically, if the number of rows having CRC errors includedtherein is greater than the maximum number of errors (i.e., 48 errors)that can be corrected by the RS erasure decoding process, either an RSerasure decoding process or a general RS decoding process is performedon a column that is decided based upon the reliability information ofthe reliability map, in accordance with the number of erasure pointswithin the corresponding column. For example, it is assumed that thenumber of rows having CRC errors included therein within the RS frame isgreater than 48. And, it is also assumed that the number of erasurepoints decided based upon the reliability information of the reliabilitymap is indicated as 40 erasure points in the first column and as erasurepoints in the second column. In this case, a (235,187)-RS erasuredecoding process is performed on the first column. Alternatively, a(235,187)-RS decoding process is performed on the second column. Whenerror correction decoding is performed on all column directions withinthe RS frame by using the above-described process, the 48-byte paritydata which were added at the end of each column are removed, as shown inFIG. 37( f).

As described above, even though the total number of CRC errorscorresponding to each row within the RS frame is greater than themaximum number of errors that can be corrected by the RS erasuredecoding process, when the number of bytes determined to have a lowreliability level, based upon the reliability information on thereliability map within a particular column, while performing errorcorrection decoding on the particular column. Herein, the differencebetween the general RS decoding process and the RS erasure decodingprocess is the number of errors that can be corrected. Morespecifically, when performing the general RS decoding process, thenumber of errors corresponding to half of the number of parity bytes(i.e., (number of parity bytes)/2) that are inserted during the RSencoding process may be error corrected (e.g., 24 errors may becorrected). Alternatively, when performing the RS erasure decodingprocess, the number of errors corresponding to the number of paritybytes that are inserted during the RS encoding process may be errorcorrected (e.g., 48 errors may be corrected).

After performing the error correction decoding process, as describedabove, a RS frame configured of 187 N-byte rows (or packets) may beobtained, as shown in FIG. 37( f). Furthermore, the RS frame having thesize of N*187 bytes is sequentially outputted in N number of 187-byteunits. Herein, as shown in FIG. 37( g), the 1-byte MPEG synchronizationbyte that was removed by the transmitting system is added at the end ofeach 187-byte packet, thereby outputting 188-byte mobile service datapackets.

When RS frame encoding is performed as shown in FIG. 6, FIG. 38illustrates process steps of an error correction decoding processperformed by the RS frame decoder 907 according to an embodiment of thepresent invention. More specifically, the RS frame decoder 907 groupsmobile service data bytes received from the data deformatter 906 so asto configure a RS frame. The mobile service data correspond to data RSencoded and CRC encoded from the transmitting system. FIG. 38( a)illustrates an example of configuring the RS frame. More specifically,the transmitting system divided the RS frame having the size of(N+2)*235 into 30*235 byte blocks. When it is assumed that each of thedivided mobile service data byte blocks is inserted in each data groupand then transmitted, the receiving system also groups the 30*235 mobileservice data byte blocks respectively inserted in each data group,thereby configuring an RS frame having the size of (N+2)*235. Forexample, when it is assumed that an RS frame is divided into 18 30*235byte blocks and transmitted from a burst section, the receiving systemalso groups the mobile service data bytes of 18 data groups within thecorresponding burst section, so as to configure the RS frame.Furthermore, when it is assumed that N is equal to 538 (i.e., N=538),the RS frame decoder 907 may group the mobile service data bytes withinthe 18 data groups included in a burst so as to configure a RS framehaving the size of 540*235 bytes.

Herein, when it is assumed that the block decoder 905 outputs a softdecision value for the decoding result, the RS frame decoder 907 maydecide the ‘0’ and ‘1’ of the corresponding bit by using the codes ofthe soft decision value. 8 bits that are each decided as described aboveare grouped to create 1 data byte. If the above-described process isperformed on all soft decision values of the 18 data groups included ina single burst, the RS frame having the size of 540*235 bytes may beconfigured. Additionally, the present invention uses the soft decisionvalue not only to configure the RS frame but also to configure areliability map. Herein, the reliability map indicates the reliabilityof the corresponding data byte, which is configured by grouping 8 bits,the 8 bits being decided by the codes of the soft decision value.

For example, when the absolute value of the soft decision value exceedsa pre-determined threshold value, the value of the corresponding bit,which is decided by the code of the corresponding soft decision value,is determined to be reliable. Conversely, when the absolute value of thesoft decision value does not exceed the pre-determined threshold value,the value of the corresponding bit is determined to be unreliable.Thereafter, if even a single bit among the 8 bits, which are decided bythe codes of the soft decision value and group to configure 1 data byte,is determined to be unreliable, the corresponding data byte is marked onthe reliability map as an unreliable data byte.

Herein, determining the reliability of 1 data byte is only exemplary.More specifically, when a plurality of data bytes (e.g., at least 4 databytes) are determined to be unreliable, the corresponding data bytes mayalso be marked as unreliable data bytes within the reliability map.Conversely, when all of the data bits within the 1 data byte aredetermined to be reliable (i.e., when the absolute value of the softdecision values of all 8 bits included in the 1 data byte exceed thepredetermined threshold value), the corresponding data byte is marked tobe a reliable data byte on the reliability map. Similarly, when aplurality of data bytes (e.g., at least 4 data bytes) are determined tobe reliable, the corresponding data bytes may also be marked as reliabledata bytes within the reliability map. The numbers proposed in theabove-described example are merely exemplary and, therefore, do notlimit the scope or spirit of the present invention.

The process of configuring the RS frame and the process of configuringthe reliability map both using the soft decision value may be performedat the same time. Herein, the reliability information within thereliability map is in a one-to-one correspondence with each byte withinthe RS frame. For example, if a RS frame has the size of 540*235 bytes,the reliability map is also configured to have the size of 540*235bytes. FIG. 38( a′) illustrates the process steps of configuring thereliability map according to the present invention. Meanwhile, if a RSframe is configured to have the size of (N+2)*235 bytes, the RS framedecoder 907 performs a CRC syndrome checking process on thecorresponding RS frame, thereby verifying whether any error has occurredin each row. Subsequently, as shown in FIG. 38( b), a 2-byte checksum isremoved to configure an RS frame having the size of N*235 bytes. Herein,the presence (or existence) of an error is indicated on an error flagcorresponding to each row. Similarly, since the portion of thereliability map corresponding to the CRC checksum has hardly anyapplicability, this portion is removed so that only N*235 number of thereliability information bytes remain, as shown in FIG. 38( b′).

After performing the CRC syndrome checking process, the RS frame decoder907 performs RS decoding in a column direction. Herein, a RS erasurecorrection process may be performed in accordance with the number of CRCerror flags. More specifically, as shown in FIG. 38( c), the CRC errorflag corresponding to each row within the RS frame is verified.Thereafter, the RS frame decoder 907 determines whether the number ofrows having a CRC error occurring therein is equal to or smaller thanthe maximum number of errors on which the RS erasure correction may beperformed, when performing the RS decoding process in a columndirection. The maximum number of errors corresponds to a number ofparity bytes inserted when performing the RS encoding process. In theembodiment of the present invention, it is assumed that 48 parity byteshave been added to each column.

If the number of rows having the CRC errors occurring therein is smallerthan or equal to the maximum number of errors (i.e., 48 errors accordingto this embodiment) that can be corrected by the RS erasure decodingprocess, a (235,187)-RS erasure decoding process is performed in acolumn direction on the RS frame having 235 N-byte rows, as shown inFIG. 38( d). Thereafter, as shown in FIG. 38( f), the 48-byte paritydata that have been added at the end of each column are removed.Conversely, however, if the number of rows having the CRC errorsoccurring therein is greater than the maximum number of errors (i.e., 48errors) that can be corrected by the RS erasure decoding process, the RSerasure decoding process cannot be performed. In this case, the errormay be corrected by performing a general RS decoding process. Inaddition, the reliability map, which has been created based upon thesoft decision value along with the RS frame, may be used to furtherenhance the error correction ability (or performance) of the presentinvention.

More specifically, the RS frame decoder 907 compares the absolute valueof the soft decision value of the block decoder 905 with thepre-determined threshold value, so as to determine the reliability ofthe bit value decided by the code of the corresponding soft decisionvalue. Also, 8 bits, each being determined by the code of the softdecision value, are grouped to form 1 data byte. Accordingly, thereliability information on this 1 data byte is indicated on thereliability map. Therefore, as shown in FIG. 38( e), even though aparticular row is determined to have an error occurring therein basedupon a CRC syndrome checking process on the particular row, the presentinvention does not assume that all bytes included in the row have errorsoccurring therein. The present invention refers to the reliabilityinformation of the reliability map and sets only the bytes that havebeen determined to be unreliable as erroneous bytes. In other words,with disregard to whether or not a CRC error exists within thecorresponding row, only the bytes that are determined to be unreliablebased upon the reliability map are set as erasure points.

According to another method, when it is determined that CRC errors areincluded in the corresponding row, based upon the result of the CRCsyndrome checking result, only the bytes that are determined by thereliability map to be unreliable are set as errors. More specifically,only the bytes corresponding to the row that is determined to haveerrors included therein and being determined to be unreliable based uponthe reliability information, are set as the erasure points. Thereafter,if the number of error points for each column is smaller than or equalto the maximum number of errors (i.e., 48 errors) that can be correctedby the RS erasure decoding process, an RS erasure decoding process isperformed on the corresponding column. Conversely, if the number oferror points for each column is greater than the maximum number oferrors (i.e., 48 errors) that can be corrected by the RS erasuredecoding process, a general decoding process is performed on thecorresponding column.

More specifically, if the number of rows having CRC errors includedtherein is greater than the maximum number of errors (i.e., 48 errors)that can be corrected by the RS erasure decoding process, either an RSerasure decoding process or a general RS decoding process is performedon a column that is decided based upon the reliability information ofthe reliability map, in accordance with the number of erasure pointswithin the corresponding column. For example, it is assumed that thenumber of rows having CRC errors included therein within the RS frame isgreater than 48. And, it is also assumed that the number of erasurepoints decided based upon the reliability information of the reliabilitymap is indicated as 40 erasure points in the first column and as erasurepoints in the second column. In this case, a (235,187)-RS erasuredecoding process is performed on the first column. Alternatively, a(235,187)-RS decoding process is performed on the second column. Whenerror correction decoding is performed on all column directions withinthe RS frame by using the above-described process, the 48-byte paritydata which were added at the end of each column are removed, as shown inFIG. 38( f).

As described above, even though the total number of CRC errorscorresponding to each row within the RS frame is greater than themaximum number of errors that can be corrected by the RS erasuredecoding process, when the number of bytes determined to have a lowreliability level, based upon the reliability information on thereliability map within a particular column, while performing errorcorrection decoding on the particular column. Herein, the differencebetween the general RS decoding process and the RS erasure decodingprocess is the number of errors that can be corrected. Morespecifically, when performing the general RS decoding process, thenumber of errors corresponding to half of the number of parity bytes(i.e., (number of parity bytes)/2) that are inserted during the RSencoding process may be error corrected (e.g., 24 errors may becorrected). Alternatively, when performing the RS erasure decodingprocess, the number of errors corresponding to the number of paritybytes that are inserted during the RS encoding process may be errorcorrected (e.g., 48 errors may be corrected). In the above-describedexample, it was assumed that 50 error points have been marked in thesecond column. Therefore, if a general RS encoding process is performedon the second column, only 24 errors are corrected, and the other 26errors are not corrected.

In this case, since one column is configured of 187 bytes, as shown inFIG. 6( c), one packet unit is considered as the basic unit forperforming RS encoding and decoding. Therefore, after performing RSdecoding on each of the columns, the system may know whether or noterror correction has been successfully performed on the correspondingpacket. For example, after RS decoding the second column, the system mayrecognize whether or not one or more errors exits in the 187-byte packetinserted in the second column. In the example given in the presentinvention, information as to whether or not an error exists within the187-byte packet is indicated on a TP error flag within a header of thecorresponding packet. In the above-described example, 26 errors stillremain in the second column, even after the second column has been RSdecoded. Therefore, information that errors still exist is marked on theTP error flag of the packet corresponding to the second column.Furthermore, all errors in the first column have been corrected afterprocessing the first column with RS decoding. Therefore, informationthat no error exists is marked on the TP error flag of the packetcorresponding to the first column. Similarly, with respect to columns inwhich no error has occurred, information that no error exists is markedon the TS error flag of the corresponding packet.

It is preferable to indicate information on whether or not one or moreerrors exist on the TP error flag after the derandomizer 908 hasderandomized the corresponding data packet. In this case, the RS framedecoder 907 only transmits information on whether or not one or moreerrors exist within the corresponding column (i.e., packet). Herein, theinformation on whether or not one or more errors exist within acorresponding column, which is (or to be) indicated on the TP error flagwithin the header of the corresponding packet, corresponds to additionalinformation on the corresponding packet. Reference is made to thisadditional information in later processes (e.g., by the video decoder).For example, when decoding a packet, the video decoder may performdecoding on the corresponding packet based upon the error informationindicated on the TP flag within the packet that is to be decoded.Alternatively, the video decoder may also disregard the correspondingpacket and not decode the packet. Furthermore, the video decoder mayalso process the corresponding packet by using a different method.

Meanwhile, after the RS frame decoder 907 performs an RS decodingprocess, as shown in FIG. 38( d) or FIG. 38( e), an RS frame configuredof 187 N-byte rows, as shown in FIG. 38( f). Thereafter, the RS framehaving the size of N*187 bytes is sequentially outputted in N number of187-byte units. More specifically, an outputted column becomes a datapacket having the size of 187 bytes, as shown in FIG. 6( b). Herein, asshown in FIG. 38( g), the 1-byte MPEG synchronization byte that wasremoved by the transmitting system is added at the end of each 187-bytepacket, thereby outputting 188-byte mobile service data packets.

FIG. 39 illustrates a process of grouping a plurality of data groups(e.g., 18 data groups) to create a RS frame and a RS frame reliabilitymap, and also a process of performing data deinterleaving in super frameunits as an inverse process of the transmitting system and identifyingthe deinterleaved RS frame and RS frame reliability map. Morespecifically, the RS frame decoder 907 groups the inputted mobileservice data so as to create a RS frame. The mobile service data havebeen RS-encoded RS frame units by the transmitting system, and theninterleaved in super frame units. At this point, the error correctionencoding process (e.g., the CRC encoding process) may have beenperformed on the mobile service data (as shown in FIG. 5), or may nothave been performed on the mobile service data (as shown in FIG. 7).

If it is assumed that the transmitting system has divided the RS framehaving the size of (N+2)*(187+P) bytes into M number of data groups(wherein, for example, M is equal to 18) and then transmitted thedivided RS frame, the receiving system groups the mobile service data ofeach data group, as shown in FIG. 39( a), so as to create a RS framehaving the size of (N+2)*(187+P) bytes. At this point, if a dummy bytehas been added to at least one of the data groups configuring thecorresponding RS frame and, then, transmitted, the dummy byte isremoved, and a RS frame and a RS frame reliability map are created. Forexample, as shown in FIG. 21, if K number of dummy bytes has been added,the RS frame and RS frame reliability map are created after the K numberof dummy bytes has been removed.

Furthermore, if it is assumed that the RS frame is divided into 18 datagroups, which are then transmitted from a single burst section, thereceiving system also groups mobile service data of 18 data groupswithin the corresponding burst section, thereby creating the RS frame.Herein, when it is assumed that the block decoder 905 outputs a softdecision value for the decoding result, the RS frame decoder may decidethe ‘0’ and ‘1’ of the corresponding bit by using the codes of the softdecision value. 8 bits that are each decided as described above aregrouped to create one data byte. If the above-described process isperformed on all soft decision values of the 18 data groups included ina single burst, the RS frame having the size of (N+2)*(187+P) bytes maybe configured. Additionally, the present invention uses the softdecision value not only to configure the RS frame but also to configurea reliability map. Herein, the reliability map indicates the reliabilityof the corresponding data byte, which is configured by grouping 8 bits,the 8 bits being decided by the codes of the soft decision value.

For example, when the absolute value of the soft decision value exceedsa pre-determined threshold value, the value of the corresponding bit,which is decided by the code of the corresponding soft decision value,is determined to be reliable. Conversely, when the absolute value of thesoft decision value does not exceed the pre-determined threshold value,the value of the corresponding bit is determined to be unreliable.Thereafter, if even a single bit among the 8 bits, which are decided bythe codes of the soft decision value and group to configure one databyte, is determined to be unreliable, the corresponding data byte ismarked on the reliability map as an unreliable data byte.

Herein, determining the reliability of one data byte is only exemplary.More specifically, when a plurality of data bytes (e.g., at least 4 databytes) are determined to be unreliable, the corresponding data bytes mayalso be marked as unreliable data bytes within the reliability map.Conversely, when all of the data bits within the one data byte aredetermined to be reliable (i.e., when the absolute value of the softdecision values of all 8 bits included in the one data byte exceed thepredetermined threshold value), the corresponding data byte is marked tobe a reliable data byte on the reliability map. Similarly, when aplurality of data bytes (e.g., at least 4 data bytes) are determined tobe reliable, the corresponding data bytes may also be marked as reliabledata bytes within the reliability map. The numbers proposed in theabove-described example are merely exemplary and, therefore, do notlimit the scope or spirit of the present invention.

The process of configuring the RS frame and the process of configuringthe reliability map both using the soft decision value may be performedat the same time. Herein, the reliability information within thereliability map is in a one-to-one correspondence with each byte withinthe RS frame. For example, if a RS frame has the size of (N+2)*(187+P)bytes, the reliability map is also configured to have the size of(N+2)*(187+P) bytes. FIG. 39( a′) and FIG. 39( b′) respectivelyillustrate the process steps of configuring the reliability mapaccording to the present invention.

At this point, the RS frame of FIG. 39( b) and the RS frame reliabilitymap of FIG. 39( b′) are interleaved in super frame units (as shown inFIG. 8). Therefore, the RS frame and the RS frame reliability maps aregrouped to create a super frame and a super frame reliability map.Subsequently, as shown in FIG. 39( c) and FIG. 39( c′), a de-permutation(or deinterleaving) process is performed in super frame units on the RSframe and the RS frame reliability maps, as an inverse process of thetransmitting system. Then, when the de-permutation process is performedin super frame units, the processed data are divided into de-permuted(or deinterleaved) RS frames having the size of (N+2)*(187+P) bytes andde-permuted RS frame reliability maps having the size of (N+2)*(187+P)bytes, as shown in FIG. 39( d) and FIG. 39( d′). Subsequently, the RSframe reliability map is used on the divided RS frames so as to performerror correction.

FIG. 40 and FIG. 41 illustrate example of the error correction processedaccording to embodiments of the present invention. FIG. 40 illustratesan example of performing an error correction process when thetransmitting system has performed both RS encoding and CRC encodingprocesses on the RS frame (as shown in FIG. 5). And, FIG. 41 illustratesan example of performing an error correction process when thetransmitting system has performed only the RS encoding process and notthe CRC encoding process on the RS frame (as shown in FIG. 7).Hereinafter, the error correction process will now be described indetail with reference to FIG. 40.

As shown in FIG. 40( a) and FIG. 40( a′), when the RS frame having thesize of (N+2)*(187+P) bytes and the RS frame reliability map having thesize of (N+2)*(187+P) bytes are created, a CRC syndrome checking processis performed on the created RS frame, thereby verifying whether anyerror has occurred in each row. Subsequently, as shown in FIG. 40( b), a2-byte checksum is removed to configure an RS frame having the size ofN*(187+P) bytes. Herein, the presence (or existence) of an error isindicated on an error flag corresponding to each row. Similarly, sincethe portion of the reliability map corresponding to the CRC checksum hashardly any applicability, this portion is removed so that only N*(187+P)number of the reliability information bytes remain, as shown in FIG. 40(b′).

After performing the CRC syndrome checking process, as described above,a RS decoding process is performed in a column direction. Herein, a RSerasure correction process may be performed in accordance with thenumber of CRC error flags. More specifically, as shown in FIG. 40( c),the CRC error flag corresponding to each row within the RS frame isverified. Thereafter, the RS frame decoder 907 determines whether thenumber of rows having a CRC error occurring therein is equal to orsmaller than the maximum number of errors on which the RS erasurecorrection may be performed, when performing the RS decoding process ina column direction. The maximum number of errors corresponds to P numberof parity bytes inserted when performing the RS encoding process. In theembodiment of the present invention, it is assumed that 48 parity byteshave been added to each column (i.e., P=48).

If the number of rows having the CRC errors occurring therein is smallerthan or equal to the maximum number of errors (i.e., 48 errors accordingto this embodiment) that can be corrected by the RS erasure decodingprocess, a (235,187)-RS erasure decoding process is performed in acolumn direction on the RS frame having (187+P) number of N-byte rows(i.e., 235 N-byte rows), as shown in FIG. 40( d). Thereafter, as shownin FIG. 40( e), the 48-byte parity data that have been added at the endof each column are removed. Conversely, however, if the number of rowshaving the CRC errors occurring therein is greater than the maximumnumber of errors (i.e., 48 errors) that can be corrected by the RSerasure decoding process, the RS erasure decoding process cannot beperformed. In this case, the error may be corrected by performing ageneral RS decoding process. In addition, the reliability map, which hasbeen created based upon the soft decision value along with the RS frame,may be used to further enhance the error correction ability (orperformance) of the present invention.

More specifically, the RS frame decoder 907 compares the absolute valueof the soft decision value of the block decoder 905 with thepre-determined threshold value, so as to determine the reliability ofthe bit value decided by the code of the corresponding soft decisionvalue. Also, 8 bits, each being determined by the code of the softdecision value, are grouped to form one data byte. Accordingly, thereliability information on this one data byte is indicated on thereliability map. Therefore, as shown in FIG. 40( c), even though aparticular row is determined to have an error occurring therein basedupon a CRC syndrome checking process on the particular row, the presentinvention does not assume that all bytes included in the row have errorsoccurring therein. The present invention refers to the reliabilityinformation of the reliability map and sets only the bytes that havebeen determined to be unreliable as erroneous bytes. In other words,with disregard to whether or not a CRC error exists within thecorresponding row, only the bytes that are determined to be unreliablebased upon the reliability map are set as erasure points.

According to another method, when it is determined that CRC errors areincluded in the corresponding row, based upon the result of the CRCsyndrome checking result, only the bytes that are determined by thereliability map to be unreliable are set as errors. More specifically,only the bytes corresponding to the row that is determined to haveerrors included therein and being determined to be unreliable based uponthe reliability information, are set as the erasure points. Thereafter,if the number of error points for each column is smaller than or equalto the maximum number of errors (i.e., 48 errors) that can be correctedby the RS erasure decoding process, an RS erasure decoding process isperformed on the corresponding column. Conversely, if the number oferror points for each column is greater than the maximum number oferrors (i.e., 48 errors) that can be corrected by the RS erasuredecoding process, a general decoding process is performed on thecorresponding column.

More specifically, if the number of rows having CRC errors includedtherein is greater than the maximum number of errors (i.e., 48 errors)that can be corrected by the RS erasure decoding process, either an RSerasure decoding process or a general RS decoding process is performedon a column that is decided based upon the reliability information ofthe reliability map, in accordance with the number of erasure pointswithin the corresponding column. For example, it is assumed that thenumber of rows having CRC errors included therein within the RS frame isgreater than 48. And, it is also assumed that the number of erasurepoints decided based upon the reliability information of the reliabilitymap is indicated as 40 erasure points in the first column and as erasurepoints in the second column. In this case, a (235,187)-RS erasuredecoding process is performed on the first column. Alternatively, a(235,187)-RS decoding process is performed on the second column. Whenerror correction decoding is performed on all column directions withinthe RS frame by using the above-described process, the 48-byte paritydata which were added at the end of each column are removed, as shown inFIG. 40( e).

As described above, even though the total number of CRC errorscorresponding to each row within the RS frame is greater than themaximum number of errors that can be corrected by the RS erasuredecoding process, when the number of bytes determined to have a lowreliability level, based upon the reliability information on thereliability map within a particular column, while performing errorcorrection decoding on the particular column. Herein, the differencebetween the general RS decoding process and the RS erasure decodingprocess is the number of errors that can be corrected. Morespecifically, when performing the general RS decoding process, thenumber of errors corresponding to half of the number of parity bytes(i.e., (number of parity bytes)/2) that are inserted during the RSencoding process may be error corrected (e.g., 24 errors may becorrected). Alternatively, when performing the RS erasure decodingprocess, the number of errors corresponding to the number of paritybytes that are inserted during the RS encoding process may be errorcorrected (e.g., 48 errors may be corrected).

After performing the error correction decoding process, as describedabove, a RS frame configured of 187 N-byte rows (or packet) may beobtained as shown in FIG. 40( e). The RS frame having the size of N*187bytes is outputted by the order of N number of 187-byte units. At thispoint, 1 MPEG synchronization byte, which had been removed by thetransmitting system, is added to each 187-byte packet, as shown in FIG.40( f). Therefore, a 188-byte unit mobile service data packet isoutputted. Hereinafter, another error correction process will bedescribed in detail with reference to FIG. 41.

As shown in FIG. 41( a) and FIG. 41( a′), when the RS frame having thesize of (N+2)*(187+P) bytes and the RS frame reliability map having thesize of (N+2)*(187+P) bytes are created, reference is made to areliability map with respect to the RS frame, so as to perform a RSdecoding process in a column direction. Referring to FIG. 41, since aCRC encoding process has not been performed on the mobile service databy the transmitting system, the CRC syndrome checking process isomitted. Therefore, a CRC error flag which is to be referred to duringthe RS decoding process does not exist. In other words, the system isunable to determine whether an error exists in each row or not.Therefore, in performing RS decoding in each column as shown in FIG. 41,the RS decoding process is performed by referring to a reliability map,which was created along with the RS frame by using the soft decisionvalue.

FIG. 41( b) and FIG. 41( b′) respectively illustrate more detailed viewsof the RS frame having the size of (N+2)*(187+P) bytes and the RS framereliability map having the size of (N+2)*(187+P) bytes. Herein, FIG. 41(b) and FIG. 41(b′) represent the same RS frame and RS frame reliabilitymap as those shown in FIG. 41( a) and FIG. 41( a′). More specifically,the RS frame decoder 907 compares an absolute value of the soft decisionvalue of the block decoder 905 with a pre-determined threshold value, soas to determine the reliability of bit value, which is decided by a codeof the corresponding soft decision value. Further, 8 bits determined bythe codes of the soft decision values are grouped to form a byte. And,the reliability information of the corresponding byte is marked in thereliability map. Therefore, the present invention determines a data byteto be erroneous (or to have errors included therein) when the systemdecides that the corresponding data byte is not reliable based upon thereliability information within the reliability map, as shown in FIG. 41(c). More specifically, only the data bytes determined to be unreliablebased upon the reliability information within the reliability map areset as erasure points.

Thereafter, when the number of error points for each column is equal toor smaller than the maximum number (P) of errors that can be correctedby RS erasure decoding (e.g., when P=48), a RS erasure decoding processis performed on the corresponding column. Conversely, when the number oferror points for each column is greater than the maximum number (P) oferrors that can be corrected by RS erasure decoding (e.g., when P=48), ageneral RS decoding process is performed on the corresponding column.For example, it is assumed that the number of erasure points decidedbased upon the reliability information of the reliability map within theRS frame is marked as ‘40’ in the first column and marked as ‘50’ in thesecond column. Then, (235,187)-RS erasure decoding is performed on thefirst column, and (235,187)-RS decoding is performed on the secondcolumn.

Meanwhile, in decoding each column, another method of referring to thereliability information includes performing a general RS decodingprocess, when the number of unreliable data bytes is smaller than P/2,performing a RS erasure decoding process, when the number of unreliabledata bytes is greater than P/2 and smaller than P, and performing ageneral RS decoding process, when the number of unreliable data bytes isgreater than P. At this point, depending upon the threshold valuedeciding the reliability information or other particular situations, thefirst reference method may provide a more enhanced performance.Alternatively, in other case, the second reference method may providebetter performance.

The selecting of the appropriate RS decoding method does not only applyin the structure shown in FIG. 41. The selecting of the appropriate andeffective RS decoding method also applies in the structure shown in FIG.40. More specifically, only the method of decoding all of the columnswith the same erasure point, when the number of CRC errors is smallerthan P, is described and illustrated in FIG. 40. However, as anotherdecoding method, the process may be more fractionalized even when thenumber of CRC errors is smaller than or equal to P. In other words, a RSdecoding process is performed, when the number of CRC errors is smallerthan or equal to P/2. And, a RS erasure decoding process may beperformed, when the number of CRC errors is greater than P/2 and smallerthan or equal to P. Similarly, when the number of CRC errors is greaterthan P, reference is made to both CRC error information and reliabilityinformation of each data byte within the reliability map. Accordingly,when the number of data bytes included in a row indicating the CRC errorand, at the same time, determined to have unreliable reliabilityinformation is smaller than or equal to P/2, a RS decoding process isperformed. When the number of such data bytes is greater than P/2 andsmaller than or equal to P, a RS erasure decoding process is performed.Finally, when the number of such data bytes is greater than P, a RSdecoding process may be performed. Furthermore, according to anotherembodiment of the present invention, based upon whether the number ofunreliable data bytes is smaller than or equal to P or whether thenumber of unreliable data bytes is greater than P, the system decideswhether to perform a RS erasure decoding process or a general RSdecoding process.

Meanwhile, by performing the above-described process so as to perform anerror correction decoding process in all column directions within the RSframe, 48 bytes of parity data, which were added to the last portion ofeach column, are removed, as shown in FIG. 41( d). As described above,in performing an error correction decoding process on a specific columnwithin the corresponding RS frame, when the number of data bytes havinga low reliability level based upon the reliability information in thereliability map of the corresponding column is equal to or smaller thana maximum number of error that can be corrected by a RS erasure decodingprocess, the present invention may perform a RS erasure decoding processof the corresponding column.

After performing the error correction decoding process, as describedabove, a RS frame configured of 187 (N+2)-byte rows (i.e., packets), asshown in FIG. 41( d). The RS frame having the size of (N+2)*(187+P)bytes is outputted by the order of (N+2) number of 187-byte units. Atthis point, 1 MPEG synchronization byte, which had been removed by thetransmitting system, is added to each 187-byte packet, as shown in FIG.41( e). Therefore, a 188-byte unit mobile service data packet isoutputted.

FIG. 42 illustrates process steps of double error correction decodingperformed by the RS frame decoder 907 according to an embodiment of thepresent invention, when a double error correction encoding process hasbeen performed in an earlier process, as shown in FIG. 11. Beforeperforming the double error correction decoding process, the RS framedecoder 907 first groups a plurality of inputted mobile service databytes to form a RS frame. Then, the RS frame decoder 907 groups G numberof RS frames to form a super frame consisting of 82*G number of rows.Subsequently, the RS frame decoder 907 performs a reverse process of rowpermutation on the super frame, which consists of 82*G number of195-byte rows. Thus, the rows are realigned back to their initial stateprior to being processed with row permutation by the transmittingsystem. Thereafter, the processed super frame is divided into G numberof RS frames configured of 82 195-byte rows.

Then, the double error correction decoding process is performed as areverse process of the double error correction encoding processperformed by the transmitting system. For example, when a primary RSencoding process is performed in a row direction, and when a secondaryRS encoding process is performed in a column direction on the primarilyRS encoded data, as shown in FIG. 11, the RS frame decoder 907 performsa primary RS decoding process on each RS frame in a column direction,and, then, performs a secondary RS decoding process on each of theprimarily RS decoded RS frames in a row direction. Afterwards, basedupon a predetermined condition, either the primary and secondary RSdecoding processes are repeated, or the decoding process is terminated.

Herein, a plurality of conditions may be predetermined in the present.According to an embodiment of the present invention, the system maydecided whether or not to repeat the decoding process, based upon thenumber of predetermined repetition rounds and the number of errorcorrected by the secondary RS decoding process. More specifically, ifthe maximum number of possible repetition rounds has been completed, orif no further error correction occurs after performing the secondary RSdecoding process, the decoding process is terminated. However, in othercases, the primary and secondary RS decoding processes are repeated. Inorder to do so, (82,68)-RS decoding is performed in a column direction,as shown in FIG. 42( a), on each of the RS frames by the reversed rowpermutation process. Then, (195,187)-RS decoding is performed in a rowdirection on the (82,68)-RS decoded RS frames, as shown in FIG. 42( b).At this point, FIG. 42( a) performs (82,68)-RS decoding in a columndirection on the RS frames each having 82 195-byte rows. And, FIG. 42(b) performs (195,187)-RS decoding in a row direction on the RS frameseach having 68 195-byte rows.

After performing (195,187)-RS decoding in a row direction, the systemverifies whether the maximum number of possible repetition rounds hasbeen completed, or whether no further error correction occurs afterperforming the RS decoding process in a row direction, as shown in FIG.42( c). At this point, if the maximum number of possible repetitionrounds still remains, and if at least one or more error-corrected databytes are corrected by the RS decoding process, which is performed in arow direction, exist, the process returns to the step shown in FIG. 42(a). Accordingly, RS decoding is performed once again on the RS frame,which has been processed with RS-decoding in a row direction.

More specifically, when one or more error-corrected data bytes exist inthe result of a row-direction RS-decoding process, and if a RS-decodingprocess is performed once again in a column direction on the RS frameRS-decoded in a row direction, additional error-correction may beperformed during the column-direction RS-decoding process. Similarly,when RS-decoding is performed once again in a row direction on theadditionally error-corrected RS frame by the column-directionRS-decoding process, additional error-correction may also be performed.Therefore, in the present invention, when one or more error-correcteddata byte exist in the row-direction RS-decoded result, and when thepredetermined number of repetition rounds still remains uncompleted, thecolumn-direction and row-direction RS-decoding processes are repeatedwhile applying the previously error-corrected result in order to enhancethe decoding performance.

At this point, when the column-direction and row-direction RS decodingprocesses are performed repeatedly, the errors may be continuouslycorrected, thereby enhancing the decoding performance. However, in aparticular erroneous state, when an error is corrected by an RS-decodingprocess performed in a column direction, another error may newly occurin a row direction. And, when an error is corrected by an RS-decodingprocess performed in row direction, another error may newly occur in acolumn direction. In order to prevent such defective results (or viciouscircle) from occurring, the system according to the present inventionlimits the number of repetitions of the RS-decoding process.

Furthermore, when an error-corrected data byte no longer exists in therow-direction RS-decoded result, this indicates that no error remains inthe corresponding RS frame. And so, the RS-decoding process is no longerrequired to be repeated. Therefore, referring to FIG. 42( c), if themaximum number of possible repetition rounds is completed, or if anerror-corrected data byte corrected by the row-direction RS-decodingprocess no longer exists, the RS-decoding process is completed, as shownin FIG. 42( d). Thereafter, the 14-byte parity data, which have beenadded to the end of each column during the double RS-encoding process,and the 8-byte parity data, which have been added to the end of eachrow, are removed from the processed data. Accordingly, 68 187-byte rows(or packets) may be obtained. Finally, referring to FIG. 42( e), theMPEG synchronization byte, which was removed by the transmitting system,is added at the very beginning of each 187-byte row, thereby outputtinga mobile service TS packet that is recovered to 188 data bytes. Theabove-described double RS-decoding process shown in FIG. 42 is performedon data that are processed with double RS-encoding, as shown in FIG. 9.

Meanwhile, when double RS-encoding process has been performed, as shownin FIG. 12, by the transmitting system, the double RS-decoding processis performed by having the receiving system perform a RS-decodingprocess in a row direction during the primary error correction decodingprocess, and by having the same receiving system perform a RS-decodingprocess in a column direction during the secondary error correctiondecoding process. The remaining double RS-decoding process steps areidentical to those described with reference to FIG. 42. Therefore, adetailed description of the same will be omitted for simplicity. At thispoint, the number of rounds for repeating the RS decoding process andthe number of error-corrected data bytes may vary depending upon thedesign made by the system designer. Therefore, the present inventionwill not be limited only to the examples given in the description of thepresent invention.

FIG. 43 illustrates a flow chart showing the process steps of an errorcorrection decoding performed by the RS frame decoder 907 according toan embodiment of the present invention, when an error correctionencoding process has been performed in an earlier process, as shown inFIG. 13. For example, when decoding is performed only on the first RSsub-frames, and when, as a result, the receiving system is unable tocorrect all errors, the receiving system may perform the decodingprocess by also using the second RS sub-frame. In this embodiment of thepresent invention, when the number of error within the mobile servicedata of regions A and B (i.e., the first RS sub-frame) is equal to orgreater than a predetermined number of errors, or when the receivingsystem is unable to correct all errors by performing the decodingprocess using only the first RS sub-frame, the system additionally usesthe mobile service data of region C (i.e., the second RS sub-frame) inorder to perform the decoding process.

The RS frame decoder 907 groups G number of first RS sub-framestransmitted to regions A and B, so as to create a first super frameconsisting of 85*G number of first RS sub-frames. Also, when using a1-byte (i.e., 8-bit) CRC checksum, the RS frame decoder 907 determineswhether any error exists in each 188-byte data packet. Then, the RSframe decoder 907 removes the 1-byte CRC checksum leaving only 187bytes. Thereafter, the RS frame decoder 907 indicates the presence of anerror on an error flag corresponding to the packet. When using a 2-byte(i.e., 16-bit) CRC checksum, the RS frame decoder 907 determines whetherany error exists in each pair of 188-byte data packets. Then, the RSframe decoder 907 removes the 2-byte CRC checksum leaving only 187 bytesin each data packet. In other words, each two 187-byte data packets aregrouped to form a pair. Subsequently, the RS frame decoder 907 indicatesthe presence of an error on an error flag corresponding to each 187-bytedata packet. At this point, when a 2-byte CRC checksum is used, eachpair of data packets should be indicated either to have an error at thesame time or to have no error included therein.

After determining the presence of an error in each row using the CRCchecksum, as described above, the RS frame decoder 907 performs areverse process of the row permutation process on the first super frame,which consists of 85*G number of 187-byte data packets. Thus, the rowsare realigned back to their initial state prior to being processed withrow permutation by the transmitting system (S1901). Thereafter, theprocessed first super frame is divided into G number of first RSsub-frames each configured of 85 187-byte data packets. Herein, theerror flags, which were used to indicate the error existing in each datapacket (or row) during the row permutation process, are converted andapplied (or succeeded) to the processed data packets. Each RS frame isformed to have the same byte matrix format of 187x85.

Additionally, the RS frame decoder 907 groups G number of second RSsub-frames transmitted to region C, so as to create a second super frameconsisting of 85*G number of second RS sub-frames. The RS frame decoder907 then performs a reverse process of the row permutation process onthe second super frame. Thus, the rows are realigned back to theirinitial state prior to being processed with row permutation by thetransmitting system (S1901). Thereafter, the processed second superframe is divided into G number of second RS sub-frames each configuredof 85 14-byte data packets. At this point, since the transmitting systemdid not perform CRC encoding on the second super frame that istransmitted to region C, the receiving system does not perform CRCdecoding on the second super frame as well. After performing the reverserow permutation process, the RS frame decoder 907 performs RS decodingusing the error flags, which are used to indicate whether or not anerror exists in each packet (or row). Herein, the error flags aresucceeded along with the first RS sub-frames (S1902).

At this point, in Step 1903, the RS frame decoder 907 verifies the CRCerror flag corresponding to each row within the first RS sub-frame, soas to determine whether the number of rows of the first RS sub-frameeach having errors included therein is equal to or smaller than thetotal number of errors (i.e., Nc-Kc) that can be processed with erasurecorrection, when the RS frame decoder 907 performs column-direction RSdecoding. If the RS frame decoder 907 determines that the number offirst RS-sub-frame rows having error included therein is equal to orsmaller than the total number of errors that can be corrected by usingerasure correction, the RS frame decoder 907 performs (85,67)-RS erasuredecoding in a column direction on the first RS sub-frame having 85187-byte rows. Thereafter, the RS frame decoder 907 removes the 18-byteparity data which were added to the end of each column (S1904 andS1908).

Accordingly, an RS frame consisting of 67 187-byte rows (or packets) maybe obtained, as shown in Step 1908. Subsequently, as shown in Step 1909,the RS frame decoder 907 adds the MPEG synchronization byte, which waspreviously removed by the transmitting system, at the very beginning ofeach 187-byte row, thereby outputting a mobile service TS packet that isrecovered to 188 data bytes. Meanwhile, when the RS frame decoder 907determines, in Step 1903, that the number of rows of the first RSsub-frame each having errors included therein is larger than the totalnumber of errors (i.e., Nc-Kc) that can be processed with erasurecorrection, the RS frame decoder 907 performs (85,67)-RS decoding in acolumn direction on the first RS sub-frame consisting of 85 187-byterows (S1905). Then, after performing the (85,67)-RS decoding process,the RS frame decoder 907 verifies whether all errors existing in thefirst RS sub-frame are corrected (S1906).

When the RS frame decoder 907 determines, in Step 1906, that theexisting errors have all been corrected, based upon the result of the(85,67)-RS decoding process, the RS frame decoder 907 removes the18-byte parity data which were added to the end of each column.Accordingly, as shown in Step 1908, an RS frame consisting of 67187-byte rows (or packets) may be obtained. Thereafter, as shown in Step1909, the RS frame decoder 907 adds the MPEG synchronization byte, whichwas previously removed by the transmitting system, to the very beginningof each 187-byte row, thereby outputting a mobile service TS packet thatis recovered to 188 data bytes. Alternatively, when the RS frame decoder907 determines, in Step 1906, that not all of the existing errors havenot been corrected, based upon the result of the (85,67)-RS decodingprocess, the RS frame decoder 907 combines (or merges) the first RSsub-frame and the second RS sub-frame, thereby performing the RSdecoding process (S1907).

FIG. 44 illustrates an example of combining (or merging) the first RSsub-frame, which is transmitted to regions A and B, and the second RSsub-frame, which is transmitted to region C, in order to perform the RSdecoding process, as shown in Step 1907. When the first and second RSsub-frames each being processed with reverse row permutation are merged,an RS frame having 85 201-byte packets (or rows) may be obtained, asshown in FIG. 44( a). At this point, each of the RS frames has alreadybeen separately processed with double RS encoding. Therefore, the RSframe decoder 907 performs double RS decoding as a reverse process ofthe double RS encoding process performed by the transmitting system.

For example, when (85,67)-RS encoding is performed in a columndirection, and when (201,187)-RS encoding is performed in a rowdirection on the (85,67)-RS encoded data, as shown in FIG. 13, the RSframe decoder 907 performs (201,187)-RS decoding (i.e., primary RSencoding) is performed in a row direction, as shown in FIG. 44( a), oneach of RS frame. Subsequently, (85,67)-RS decoding (i.e., secondary RSencoding) is performed in a column direction, as shown in FIG. 44( b).At this point, FIG. 44( a) performs (201,187)-RS decoding in a rowdirection on the RS frames each having 85 201-byte rows. And, FIG. 44(b) performs (85,67)-RS decoding in a column direction on the RS frameseach having 85 187-byte rows. Afterwards, based upon a predeterminedcondition, either the column-direction and row-direction RS decodingprocesses are repeated, or the decoding process is terminated.

Alternatively, when a RS encoding process is performed in a rowdirection, and when a RS encoding process is performed in a columndirection on the primarily RS encoded data, the RS frame decoder 907first performs a RS decoding (i.e., a primary RS decoding) process oneach RS frame in a column direction, and, then, performs a RS decoding(i.e., a secondary RS decoding) process on each of the primarilyRS-decoded RS frames in a row direction. Similarly, based upon apredetermined condition, either the column-direction and row-directionRS decoding processes are repeated, or the decoding process isterminated.

Herein, a plurality of conditions may be predetermined in the present.According to an embodiment of the present invention, the system maydecided whether or not to repeat the decoding process, based upon thenumber of predetermined repetition rounds and the number of errorcorrected by the secondary RS decoding process. More specifically, ifthe maximum number of possible repetition rounds has been completed, orif no further error correction occurs after performing the secondary RSdecoding process, the decoding process is terminated. However, in othercases, the primary and secondary RS decoding processes are repeated.

After performing (85,67)-RS decoding in a column direction, as shown inFIG. 44( b), the system verifies whether the maximum number of possiblerepetition rounds has been completed, or whether no further errorcorrection occurs after performing the RS decoding process in a columndirection, as shown in FIG. 44( c). At this point, if the maximum numberof possible repetition rounds still remains, and if at least one or moreerror-corrected data bytes are corrected by the RS decoding process,which is performed in a column direction, exist, this information isfed-back to the step shown in FIG. 44( a). Accordingly, RS decoding isperformed once again in a row direction on the RS frame, which has beenprocessed with RS-decoding in a column direction.

More specifically, when one or more error-corrected data bytes exist inthe result of a column-direction RS-decoding process, and if aRS-decoding process is performed once again in a row direction on the RSframe RS-decoded in a column direction, additional error-correction maybe performed during the row-direction RS-decoding process. Similarly,when RS-decoding is performed once again in a column direction on theadditionally error-corrected RS frame by the row-direction RS-decodingprocess, additional error-correction may also be performed. Therefore,in the present invention, when one or more error-corrected data byteexist in the column-direction RS-decoded result, and when thepredetermined number of repetition rounds still remains uncompleted, therow-direction and column-direction RS-decoding processes are repeatedwhile applying the previously error-corrected result in order to enhancethe decoding performance.

At this point, when the row-direction and column-direction RS decodingprocesses are performed repeatedly, the errors may be continuouslycorrected, thereby enhancing the decoding performance. However, in aparticular erroneous state, when an error is corrected by an RS-decodingprocess performed in a row direction, another error may newly occur in acolumn direction. And, when an error is corrected by an RS-decodingprocess performed in column direction, another error may newly occur ina row direction. In order to prevent such defective results (or viciouscircle) from occurring, the system according to the present inventionlimits the number of repetitions of the RS-decoding process.

Furthermore, when an error-corrected data byte no longer exists in thecolumn-direction RS-decoded result, this indicates that no error remainsin the corresponding RS frame. And so, the RS-decoding process is nolonger required to be repeated. Therefore, referring to FIG. 44( c), ifthe maximum number of possible repetition rounds is completed, or if anerror-corrected data byte corrected by the column-direction RS-decodingprocess no longer exists, the RS-decoding process is completed, as shownin FIG. 44( d). Thereafter, the 14-byte parity data, which have beenadded to the end of each row during the double RS-encoding process, andthe 18-byte parity data, which have been added to the end of eachcolumn, are removed from the processed data. Accordingly, 67 187-byterows (or packets) may be obtained, as shown in FIG. 44( d). Finally,referring to FIG. 44( e), the MPEG synchronization byte, which wasremoved by the transmitting system, is added at the very beginning ofeach 187-byte row, thereby outputting a mobile service TS packet that isrecovered to 188 data bytes.

At this point, the number of rounds for repeating the RS decodingprocess and the number of error-corrected data bytes may vary dependingupon the design made by the system designer. Therefore, the presentinvention will not be limited only to the examples given in thedescription of the present invention. Furthermore, in RS decoding eachRS frame, when the number of rows known to have errors, based upon a CRCerror detection result, is equal to or smaller than the maximum numberof errors on which the RS erasure correction may be performed, whenperforming the RS decoding process in a column direction, the erasurecorrection process is performed as the RS decoding process in order tomaximize the error correction performance.

FIG. 45 illustrates an example of an error correction decoding processperformed by the RS frame decoder 907 according to an embodiment of thepresent invention, when an error correction encoding process has beenperformed in an earlier process, as shown in FIG. 16. Herein, the RSdecoding process may vary depending upon a sum of the number of errorsexisting in the first RS sub-frames, which are transmitted to regions Aand B, and the number of errors existing in the second RS sub-frames,which are transmitted to region C. In order to do so, the RS framedecoder 907 groups G number of first RS sub-frames transmitted toregions A and B, so as to create a first super frame consisting of 85*Gnumber of first RS sub-frames. At this point, a first RS sub-frameconsists of 85 187-byte rows (or packets), as shown in FIG. 44( a).

Also, when the transmitting system uses a 1-byte (i.e., 8-bit) CRCchecksum, the RS frame decoder 907 determines whether any error existsin each 188-byte data packet within the first super frame. Then, the RSframe decoder 907 removes the 1-byte CRC checksum leaving only 187bytes. Thereafter, the RS frame decoder 907 indicates the presence of anerror on an error flag corresponding to the packet. When using a 2-byte(i.e., 16-bit) CRC checksum, the RS frame decoder 907 determines whetherany error exists in each pair of 188-byte data packets. Then, the RSframe decoder 907 removes the 2-byte CRC checksum leaving only 187 bytesin each data packet. In other words, each two 187-byte data packets aregrouped to form a pair. Subsequently, the RS frame decoder 907 indicatesthe presence of an error on an error flag corresponding to each 187-bytedata packet. At this point, when a 2-byte CRC checksum is used, eachpair of data packets should be indicated either to have an error at thesame time or to have no error included therein.

After determining the presence of an error in each row using the CRCchecksum, as described above, the RS frame decoder 907 performs areverse process of the row permutation process on the first super frame,which consists of 85*G number of 187-byte data packets, as shown in FIG.45( b). Thus, the rows are realigned back to their initial state priorto being processed with row permutation by the transmitting system.Thereafter, the processed first super frame is divided into G number offirst RS sub-frames each configured of 85 187-byte data packets. Herein,the error flags, which were used to indicate the error existing in eachdata packet (or row) during the row permutation process, are convertedand applied (or succeeded) to the processed data packets. Additionally,the RS frame decoder 907 groups G number of second RS sub-framestransmitted to region C, so as to create a second super frame consistingof 6*G number of second RS sub-frames. At this point, a second RSsub-frame consists of 6 187-byte rows (or packets), as shown in FIG. 44(a).

Also, when the transmitting system uses a 1-byte (i.e., 8-bit) CRCchecksum, the RS frame decoder 907 determines whether any error existsin each 188-byte data packet within the second super frame. Then, the RSframe decoder 907 removes the 1-byte CRC checksum leaving only 187bytes. Thereafter, the RS frame decoder 907 indicates the presence of anerror on an error flag corresponding to the packet. When using a 2-byte(i.e., 16-bit) CRC checksum, the RS frame decoder 907 determines whetherany error exists in each pair of 188-byte data packets. Then, the RSframe decoder 907 removes the 2-byte CRC checksum leaving only 187 bytesin each data packet. In other words, each two 187-byte data packets aregrouped to form a pair. Subsequently, the RS frame decoder 907 indicatesthe presence of an error on an error flag corresponding to each 187-bytedata packet. At this point, when a 2-byte CRC checksum is used, eachpair of data packets should be indicated either to have an error at thesame time or to have no error included therein.

After determining the presence of an error in each row using the CRCchecksum, as described above, the RS frame decoder 907 performs areverse process of the row permutation process on the second superframe, which consists of 6*G number of 187-byte data packets, as shownin FIG. 45( b). Thus, the rows are realigned back to their initial stateprior to being processed with row permutation by the transmittingsystem. Thereafter, the processed second super frame is divided into Gnumber of second RS sub-frames each configured of 6 187-byte datapackets. Similarly, the error flags, which were used to indicate theerror existing in each data packet (or row) during the row permutationprocess, are converted and applied (or succeeded) to the processed datapackets.

At point, when merging the first and second RS sub-frames that areprocessed with reversed row permutation, a RS frame consisting of 91187-byte packets (or rows) may be obtained. In FIG. 45( c), the RS framedecoder 907 verifies and determines whether the total number of CRCerrors generated in the RS frame is larger than the number of paritydata bytes added to the RS frame. Herein, the total number of CRC errorsgenerated in the RS frame can be verified by referring to CRC errorflags corresponding to each row within the RS frame. And, the number ofparity data bytes added to the RS frame can be known by calculatingNc-Kc. If the total number of CRC errors generated in the RS frame isequal to or smaller than the number of parity data bytes added to the RSframe, 91 CRC error flag values corresponding to each row within the RSframe are used, as shown in FIG. 45( e), in order to perform (91,67)-RSerasure decoding with respect to each column (i.e., in a columndirection) within the RS frame. According to another embodiment of thepresent invention, if the total number of CRC errors generated in the RSframe is larger than the number of parity data bytes added to the RSframe, (91,67)-RS decoding may be performed without using the CRC errorflag values.

When RS decoding is performed on each RS frame, as shown in FIG. 45( d)or FIG. 45( e), the 24-byte parity data that were added to the end ofeach column during the RS encoding process are removed. Morespecifically, when RS decoding is performed on each RS frame, an RSframe consisting of 67 187-byte rows (or packets) may be obtained, asshown in FIG. 45( f). Finally, referring to FIG. 45( g), the MPEGsynchronization byte, which was removed by the transmitting system, isadded at the very beginning of each 187-byte row, thereby outputting amobile service TS packet that is recovered to 188 data bytes.

As described above, the digital broadcasting system and data processingmethod according to the present invention have the following advantages.More specifically, the digital broadcasting system and data processingmethod according to the present invention is robust against (orresistant to) any error that may occur when transmitting mobile servicedata through a channel. And, the present invention is also highlycompatible to the conventional system. Moreover, the present inventionmay also receive the mobile service data without any error even inchannels having severe ghost effect and noise.

By inserting known data in specific positions (or places) within a dataregion, the present invention may enhance the receiving performance ofthe receiving system in an environment undergoing frequent channelchanges. Additionally, when multiplexing the mobile service data withthe main service data, by multiplexing the data in a bus structure, thepower consumption level of the receiving system may be reduced.Moreover, by using known data information in order to perform channelequalization, the receiving system may perform channel equalization withmore stability.

Furthermore, by performing at least one of an error correction encodingprocess, an error detection encoding process, and a row permutationprocess in super frame units on the mobile service data and transmittingthe processed data, the present invention may provide robustness to themobile service data, thereby enabling the data to effectively respond tothe frequent change in channels. Finally, the present invention is evenmore effective when applied to mobile and portable receivers, which arealso liable to a frequent change in channel and which require protection(or resistance) against intense noise.

It will be apparent to those skilled in the art that variousmodifications and variations can be made in the present inventionwithout departing from the spirit or scope of the inventions. Thus, itis intended that the present invention covers the modifications andvariations of this invention provided they come within the scope of theappended claims and their equivalents.

1. A method of processing broadcast data in a broadcast transmitter, themethod comprising: Reed-Solomon (RS) encoding and Cyclic RedundancyCheck (CRC) encoding mobile service data bytes to build an RS framecomprising the mobile service data bytes; dividing the built RS frameinto a plurality of M RS frame portions; adding K bytes of dummy data toone of the plurality of RS frame portions, wherein K≧0; converting databytes of the plurality of RS frame portions into data bits; encoding theconverted data bits at a coding rate of 1/H in order to output datasymbols, wherein H≧2; interleaving the data symbols in a symbolinterleaver that interleaves the data symbols by: creating a list of allpermuted positions P′(i) in ascending order of i according to thefollowing equation:P′(i)={S*i*(i+1)/2} mod L, wherein L=2^(m), wherein m is an integer,wherein i is a natural number in a range from 0 to (L−1), and wherein Sis an integer; discarding all P′(i) that satisfy P′(i)≧B, wherein B is ablock length of the data symbols input to the symbol interleaver; andcondensing the list of all permuted positions by shifting P′(i) entriesto the left starting with a lowest i in order to fill empty locationscreated by the discarding; converting the interleaved data symbols intodata bytes; forming data groups including the converted data bytes,wherein each of the data groups further includes known data sequencesand signaling information; multiplexing mobile service data packetsincluding data of the data groups with main service data packetsincluding main service data to generate multiplexed data packets; andtransmitting a broadcast signal including data of the multiplexed datapackets, wherein a collection of the data groups is transmitted duringslots in the broadcast signal, the slots being basic time periods formultiplexing the mobile service data packets with the main service datapackets.
 2. The method of claim 1, wherein the RS frame furthercomprises an RS frame payload including the mobile service data bytes,RS parity data bytes added at bottom ends of columns of the RS framepayload, and CRC data bytes added at right ends of rows of the RS framepayload including the RS parity data bytes.
 3. The method of claim 1,further comprising: deinterleaving data of the data groups.
 4. Themethod of claim 1, further comprising: interleaving data of themultiplexed data packets; and trellis encoding the interleaved data. 5.A broadcast transmitter comprising: a first encoder for Reed-Solomon(RS) encoding and Cyclic Redundancy Check (CRC) encoding mobile servicedata bytes to build an RS frame comprising the mobile service databytes, dividing the built RS frame into a plurality of M RS frameportions and adding K bytes of dummy data to one of the plurality of RSframe portions, wherein K≧0; a byte to bit converter for converting databytes of the plurality of RS frame portions into data bits; a secondencoder for encoding the converted data bits at a coding rate of 1/H inorder to output data symbols, wherein H≧2; a symbol interleaver forinterleaving the data symbols, wherein the symbol interleaverinterleaves the data symbols by: creating a list of all permutedpositions P′(i) in ascending order of i according to the followingequation:P′(i)={S*i*(i+1)/2} mod L, wherein L=2^(m), wherein m is an integer,wherein i is a natural number in a range from 0 to (L−1), and wherein Sis an integer; discarding all P′(i) that satisfy P′(i)≧B, wherein B is ablock length of the data symbols input to the symbol interleaver, andcondensing the list of all permuted positions by shifting P′(i) entriesto the left starting with a lowest i in order to fill empty locationscreated by the discarding; a symbol to byte converter for converting theinterleaved data symbols into data bytes; a group formatting unit forforming data groups including the converted data bytes, wherein each ofthe data groups further includes known data sequences and signalinginformation; a multiplexer for multiplexing mobile service data packetsincluding data of the data groups with main service data packetsincluding main service data to generate multiplexed data packets; and atransmitting unit for transmitting a broadcast signal including data ofthe multiplexed data packets, wherein a collection of the data groups istransmitted during slots in the broadcast signal, the slots being basictime periods for multiplexing the mobile service data packets with themain service data packets.
 6. The broadcast transmitter of claim 5,wherein the RS frame further comprises an RS frame payload including themobile service data bytes, RS parity data bytes added at bottom ends ofcolumns of the RS frame payload, and CRC data bytes added at right endsof rows of the RS frame payload including the RS parity data bytes. 7.The broadcast transmitter of claim 5, further comprising: adeinterleaver for deinterleaving data of the data groups.
 8. Thebroadcast transmitter of claim 5, further comprising: an interleaver forinterleaving data of the multiplexed data packets; and a trellisencoding unit for trellis encoding the interleaved data.